Bugfix to templates

Change templateHostUrl to be non-static so it updates when you switch
between different templates.

Change-Id: I65969fef011e428a906b622855dbc1fbc1b66e70
Fixes race condition that caused duplicate template projects to be created.

Change-Id: I8907001091444f0c4d5004b76ad3b2cb5ecb08b0
Merge branch 'master' of github.com:mit-cml/appinventor-sources into moveLanguageMenu