Jetpack: GlotPress: merge to [GP785]: -- props @yoavf

[GP776] - prevent notice on import
[GP777], [GP785] - fix for translation set counts cache
[GP778], [GP779], [GP780], [GP782], [GP783]: various php 5.4 fixes, prevents notices and warnings



git-svn-id: https://plugins.svn.wordpress.org/jetpack/trunk@815475 b8457f37-d9ea-0310-8a92-e5e31aec5664