switching component drop down changes language name

this makes it possible to delete the component that was originally used to create the block http://trac.appinventor.mit.edu/ticket/397

Change-Id: I1cf56b3122ca3bc9486ba731c1456dd664422042
add show/hide warning button

warnings can now be toggled from a button inside of the designer.
also added calls in connection.js so that warnings can be triggered when a block is being connected.

Change-Id: I8abec995c5de7690b2fa85f848ade4b7752b66a4
add change handler to do-return block

Change-Id: Ib97e3f33356ac9e0eebc41149a1d998bb81cfc71
Make Yail Generation Menu on blocks contingent on being an Admin.

Only expose the "Generate Yail" option on a block if we are an
admin. Also add IntelliJ stuff to sample gitignore.

Change-Id: I5ace9bc5b9cc83e6c99bbf414ac9d66adb6edd0d