Merge pull request #77 from srijan/master

Add @headerfile tag in src/riakc_pb_socket.erl
get(...) can return unchanged, not {error, unchanged}.
Fixed broken html in documentation.
Introduced in aa9872e5e9b28f58de11564af90f6972cbff2e29
Added utility functions for user metadata and 2i
Enhanced unit tests for riak_obj
Enhanced interface flexibility.
Updated with information about metadata and secondary index functionality.
Corrected ping() spec
Updated/corrected following review.
get_metadata/1 no longer throws no_metadata exception
Updated doc and added utility functions for links.
Corrected doc formatting error.
Corrected doc formatting error.
Merge pull request #80 from anha0825/master

Edoc fix: get(...) can return unchanged, not {error, unchanged}.
Updated sibling resolution section
Updates following review
Corrected metsdata test
add get_metadata test back to newcontent0_test as well
Merge PR #82 from branch 'cd-metadata_exceptions'
Merge PR #81 from branch 'cd-doc_and_metadata_update'