Change Default Character Encoding.

Change the Default Character Encoding to UTF-8 so that Chinese
characters can be used in block names.

Change-Id: I1e6dc94fb05f6f7d54fa3a493536ad93c1c1804d
Deliver blockly-all.js in UTF-8 instead of UTF-16.

Arrange for App Engine server to provide the character set of UTF-8
for blockly-all.js in the Content-Type header. By default the browser
guesses the character set based on looking at the first "N"
characters.  Because Chinese was not used until far into the file, the
browser would incorrectly guess ISO-8859-1. UTF-16 worked because it
is a two byte encoding for *all* characters into the file, so the
browser was able to guess UTF-16 from the first N.

Also add the path of the closure library explicitly to the Plover
config file for when we actually use the compiler.

Change-Id: Ie410a6c42073188f07cc80f6dfca996f6b979c8c
Added 3 new unit tests for backgroundColor.js (initial test), as well as paintPot and moleMash to make sure the yail generation works properly. This commit also contains all of the files required for each test.
A new yail_testing_index.html is used here to compare the yail between NB and Classic. Inject.js was modified to allow the yail generator to function properly due to a call to a non-existant function, so an if statement was added just to make sure it exists before calling it.

Change-Id: I043f2ea52499afd3fe94dbd59230c04828acf97a