Conduit - Add option for createcomment to attach draft inline comments

Summary:
Conduit has a query to make a draft inline comment, but createcomment doesn't have the ability to attach them.
Added optional parameter to attach any existing draft comments. Default value is false, so existing api users won't be effected by the change.

Test Plan: Tested no draft comments and multiple draft comments, attach_inlines =true, false, and empty.

Reviewers: vrana

Reviewed By: vrana

CC: epriestley, aran

Differential Revision: https://secure.phabricator.com/D7019