Replace leading whitespace in commit message.

This allows for proper indentation to display ASCII art.

Fixes travis-ci/travis-ci#2003
Set whitespace handling via CSS.

Relevant for travis-ci/travis-ci#2003.
Wrap commit body into a pre tag.

This follows the idea that the message can contain useful things
like ASCII diagrams or wonderful art.

Related to travis-ci/travis-ci#2003.
Decrease line height for commit body slightly.

18px seems like a good compromise between ASCII art and
readability.
Show xcode_sdk and scheme as matrix dimensions.

Fixes travis-ci/travis-ci#2177.
Only show message body when it exists.

Otherwise the script will return the message subject again rather
than show nothing at all.
Trim the commit message.
Prevent sending double restart request

When requeue icon was clicked 2 times it was sometimes the case that we
sent 2 requests. This commit prevents that and also adds a little nice
indicator instead of restart button while we're sending the request.