Issue 1110: TagApi syntax for EC2

gistfile1.txt

http://code.google.com/p/jclouds/issues/detail?id=1110

In both setting and getting tags, the value is optional.  I'd suggest mapping the following syntax:

void apply(Map<String, Optional<String>> tags, Iterable<String> resourceIds)

http://docs.amazonwebservices.com/AWSEC2/latest/APIReference/ApiReference-query-CreateTags.html

FluentIterable<Tag> list();
FluentIterable<Tag> filter(Multimap<String, String> filter);

http://docs.amazonwebservices.com/AWSEC2/latest/APIReference/ApiReference-query-DescribeTags.html

FluentIterable<Tag> deleteTagsFromResources(Iterable<String> tags, Iterable<String> resourceIds)

FluentIterable<Tag> conditionalDeleteTagsFromResources(Map<String, Optional<String>> conditionalTagValues, Iterable<String> resourceIds)

http://docs.amazonwebservices.com/AWSEC2/latest/APIReference/ApiReference-query-DeleteTags.html