Test for object existence using head request.

Use the PB head option or an HTTP HEAD request.
Trimming the version number to prevent Rails error: Malformed version number string 1.4.2-0-g61ac9d8
Using split instead of truncating
Merge pull request #120 from jacepp/version-trim

Had an issue when trying to read the Riak server's version number
Merge pull request #102 from eliaslevy/exists-using-head

Test for object existence using head request.
Spec for backends turning links into a set.
turn links into a set when loading from protobuffs
fix no key/no term test
provide an explicit case for when no 2i results come back
1.4.2 release notes

Conflicts:
	RELEASE_NOTES.md
Release notes for bug 123
Fix "RObject" spelling in release notes
Fix list_buckets in http backend
Update How to Contribute in README file
Merge pull request #124 from wcamarao/fix_http_be

Fix list_buckets in http backend
Merge pull request #113 from basho/bk-yokozuna

Riak 2 Feature: Yokozuna
2i examples in README need to use Strings for index names.
Merge branch 'master' into bk-remove-http

Conflicts:
	lib/riak/client/http_backend.rb
Merge branch 'master' into bk-remove-http

Conflicts:
	lib/riak/client/http_backend.rb
	spec/riak/beefcake_protobuffs_backend_spec.rb
	spec/riak/http_backend_spec.rb
	spec/support/unified_backend_examples.rb
Merge pull request #119 from basho/bk-remove-http

Riak Client 2 Feature: Remove HTTP