add ngMessages dependency
add validators: xlink and xtype

xlink: check for URL (must be improved)
xtype: check the type of file (ie: image/png)
minor: Add a comment
Update templates: use of ngMessages
Merge branch 'form'

* form:
  Update templates: use of ngMessages
  minor: Add a comment
  add validators: xlink and xtype
  add ngMessages dependency
Improve UI: button instead of checkbox
Minor ui improvement

add margin between filters and pushes
nodeJS' package moment -› bower's package.

Pushkiwi is almost browser compatible. Need a WS client, since the one used is only for NodeJS