Add BrowserConsoleHandler

BrowserConsoleHandler is an handler sending logs to browser's javascript console
with no browser extension required
Fix PHP 5.3 support for BrowserConsoleHandler
Some consmetic changes
Fix invalid output when message contain returns
Use more "unique" markers format for styling
Allow for different Content-type and character encodings; Insert a MIME-Version header for HTML emails if there isn't one already; More documentation;
Add Rollbar handler.
Add composer suggest for Rollbar package.

Update documentation.
Inject rollbar handler.

Typecheck exceptions.
Coding standard fix.
Flush roll bar notifier on close rather than destruct.

Inherit DocBlocks.
Include context data as extra data sent to Rollbar.
Include level, channel, and datetime in extra data sent to Rollbar.
Send datetime as a string so it can be converted to JSON.
Correct spacing
Merge remote-tracking branch 'moderndeveloperllc/master'
Prevent empty headers from having a leading \r\n
Merge pull request #332 from PaulStatezny/rollbar-handler

Add Rollbar handler
Merge remote-tracking branch 'rs/browser-console-handler'
Refactor the browser console handler to keep more methods private, refs #303
Minor simplificationy of BrowserConsoleHandler