R1:bc61f36bebe1

Replace `elseif` by `else if`

Summary:
Mostly written by me.
Omit external libraries.

Test Plan: http://phabricator.com/docs/phabricator/article/PHP_Coding_Standards.html

Reviewers: epriestley

Reviewed By: epriestley

CC: aran

Differential Revision: https://secure.phabricator.com/D2104