Revert "Merge pull request #148 from dimagi/dont-delete-unknown-lang"

This reverts commit e4ae887823df5846744cb0c8430ad3b14d42f90e, reversing
changes made to ded13b64b2c2d3d0626ae18f59152e42c6150054.
improve warning for language that will be deleted
fix more type-switching bugs

the right way to do this is to probably have the Mug definition have
a list of static attributes that don't get overridden during `setAttr`
but this is a reasonable short term workaround.

http://manage.dimagi.com/default.asp?99152
Merge pull request #165 from dimagi/vellum-languages-warning

Vellum languages warning
Merge pull request #166 from dimagi/cz

fix more type-switching bugs
specify language in parse warning message
Merge pull request #167 from dimagi/fix-lang-message

specify language in parse warning message
Fix display condition consisting of spaces only

http://manage.dimagi.com/default.asp?98184
Merge pull request #168 from dimagi/fix-display-condition-spaces

Fix display condition consisting of spaces only
Merge branch 'master' of github.com:dimagi/Vellum into develop
fix input disabling