Update msl-core javascript version to 1.2226.0, specify ECMA version 5

for jshint.

Update package.json version to 1.2225.0.

Update package.json version to v1.1224.0.

Merge pull request Netflix#282 from Netflix/header-builder-subclass

Allow MessageBuilder, MessageHeader and ErrorHeader to be subclassed.

Merge pull request Netflix#276 from Netflix/release-mastertoken

Correct (hopefully) master token lock cleanup in MslControl.

Merge pull request Netflix#276 from Netflix/release-mastertoken

Correct (hopefully) master token lock cleanup in MslControl.

Make odd plaintext.

Merge pull request Netflix#270 from Netflix/no-sync-buffer-classes

Do not use synchronous Buffered classes.

Merge pull request Netflix#266 from Netflix/restore-sender

Include sender field when constructing a message header with a master token.

Merge pull request Netflix#261 from Netflix/sender-recipient

Remove sender & recipient fields; verify remote entity identity if specified.