Error: source spec/accept.sh

error.out

/fcrepo4-vagrant$ source spec/accept.sh 
Fetching gem metadata from https://rubygems.org/...........
Resolving dependencies...
Installing rake 10.5.0
Installing CFPropertyList 2.3.2
Using i18n 0.7.0
Using json 1.8.3
Installing minitest 5.8.4
Using thread_safe 0.3.5
Using tzinfo 1.2.2
Installing activesupport 4.2.5.1
Installing addressable 2.4.0
Installing mini_portile2 2.0.0

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb 
checking if the C compiler accepts ... yes
Building nokogiri using packaged libraries.
Using mini_portile version 2.0.0
checking for gzdopen() in -lz... no
zlib is missing; necessary for building libxml2
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/usr/bin/ruby2.1
        --help
        --clean
        --use-system-libraries
        --enable-static
        --disable-static
        --with-zlib-dir
        --without-zlib-dir
        --with-zlib-include
        --without-zlib-include=${zlib-dir}/include
        --with-zlib-lib
        --without-zlib-lib=${zlib-dir}/lib
        --enable-cross-build
        --disable-cross-build

extconf failed, exit code 1

Gem files will remain installed in /tmp/bundler20160222-21371-u5w5f3/nokogiri-1.6.7.2/gems/nokogiri-1.6.7.2 for inspection.
Results logged to /tmp/bundler20160222-21371-u5w5f3/nokogiri-1.6.7.2/extensions/x86_64-linux/2.1.0/nokogiri-1.6.7.2/gem_make.out
An error occurred while installing nokogiri (1.6.7.2), and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.6.7.2'` succeeds before bundling.