add base64 image input validation with test cases
Merge remote-tracking branch 'upstream/master'
only load mmmagic on server side.
when using browserify, need to use --im to ingore loading error for
require('mmmagic')
start the server_module. We should put all the server related libs into this module
in the future, so we can use browserify to ingore it for client side bundle.
Merge https://github.com/charlescao/medic-forms

Conflicts:
	lib/util.js
	tests/fixtures/input/values.json
	tests/input.js
Merge branch 'master' of https://github.com/medic/medic-forms

Conflicts:
	tests/input.js