choose form to use when creating post from message

Summary:
add popup list to choose form when creating posts from messages, fix alert, fixes T938

delinting

Test Plan: try creating posts from messages using different forms

Reviewers: rjmackay, vladimir, shadowhand

Reviewed By: shadowhand

Subscribers: srutto

Maniphest Tasks: T938

Differential Revision: https://phabricator.ushahidi.com/D454