This is a GIST to explain a workaround to the lack of case insensitive or partial text search on the server side via the Emberfire add-on.

controller.js

import Ember from 'ember';
import computed from 'ember-new-computed';

const inject = Ember.inject;
const alias  = computed.alias;
const sort   = computed.sort;

export default Ember.Controller.extend({
  sessionManager: inject.service(),
  person: alias('sessionManager.person'),
  personSkills: alias('sessionManager.personSkillsByName'),
  // This is the field bound to the autocomplete control and used for client side filtering
  filterText: "",
  // This is the field bound to query and used for server side filtering
  filterTextThree: "",

  // This will update 'filterTextThree' when 'filterText' changes and is 3 char long
  filterTextObserver: function() {
    if(this.get('filterText.length') === 3) {
      this.set('filterTextThree', this.get('filterText').toUpperCase());   
    }
  }.observes('filterText'),

  // This will pull down models based on the 'nameStartsWith' field matching against 'filterTextThree' and updates when 'filterTextThree' changes
  skillsByStartsWith: Ember.computed('filterTextThree', function() {
    if(this.get('filterTextThree')) {
      return this.store.query('skill', {
        orderBy: 'nameStartsWith',
        equalTo: this.get('filterTextThree')
      });     
    }
  }),

  // This does the client side filtering of models returned by the 'skillsByStartsWith' property
  // This however uses the full string of 'filterText' regardless of how many chars it is
  skills: Ember.computed('skillsByStartsWith', 'skillsByStartsWith.[]', 'filterText', function() {
    const promise = this.get('skillsByStartsWith');
    if(promise && promise.get('length') && this.get('filterText')) {
      const filterText = this.get('filterText').toUpperCase(); 
      return promise.filter(function(skill) {
        return skill.get('name').toUpperCase().indexOf(filterText) !== -1;
      });       
    }
  }),

  actions: {
    updateSearch(str) {
      this.set('filterText', str);        
    }
  },

  newSkill: null,
  addSkillObserver: function() {
    const self = this;
    const person = this.get('person');
    const newSkill = this.get('newSkill');
    if(newSkill) {
      this.store.createRecord('person-skill', {
        person: person,
        skill: newSkill
      }).save().then(function() {
        self.set('newSkill', null);  
        self.set('filterText', null);      
      });      
    }
  }.observes('newSkill')
});

skill.js

import DS from 'ember-data';

export default DS.Model.extend({
  name: DS.attr('string'),
  nameStartsWith: DS.attr('string')
});

skills.json

{
  "1290": {
  "name" : "Business economics (teaching)",
  "nameStartsWith" : "BUS"
  },
  "1291": {
  "name" : "Business Efficiency",
  "nameStartsWith" : "BUS"
  }
}

template.hbs

{{#paper-content class="md-padding"}}
<h2>
  Please add any skills you have.
</h2>      
<p class="cvr-black">
  We use this information to highlight your skills and to better match you with opportunities.
  <br><br>
  This information is completely optional and no one will see this unless you want them to.
</p>
{{paper-autocomplete  floating=true
                      minLength=3
                      placeholder="Enter the first 3 letters of the skill..." 
                      source=skills 
                      lookupKey="name" 
                      model=newSkill 
                      cache-miss="updateSearch"}}
{{#paper-list}}
  {{#each personSkills as |personSkill|}}
    <div class="progress-bars">
      {{#link-to 'skills.edit' personSkill tagName='div' class="progress progress-1"}}
      <div class="{{if personSkill.months 'progress-bar' 'no-progress-bar'}}" style="width: {{personSkill.ratingNumber}}%">
        <span>
          <div class="title">{{personSkill.skill.name}}</div>
          <div class="percent">{{personSkill.ratingText}}</div>
        </span>
      </div>
      {{/link-to}}
    </div>
  {{/each}}        
{{/paper-list}}
{{/paper-content}}