Support for Librato Metrics.

Refactored most of the JavaScript for this, as Librato
doesn't support fetching multiple metrics in one requests.
Most data structures were moved from multi-dimensional arrays
to hashes indexed by the metric's target.
Support Librato's display transforms.

Also remove initialization or URL on load.
Restore old metric width.

Don't round down metrics > 2. Temporary fix as this makes
2.97 be rounded down to 2.
Support for fetching specific time ranges.

Resuming live feed works as well.
Index metrics by name and source.

Allows having the same metric with different source
multiple times.
Don't barf on empty measurements.

Also avoid scoping issues with the metric's name by explicitly
handing it over to the callback.
Colons are not valid selector characters.
Make sure empty transforms don't break things.
Extract Librato Metrics code.

Basis for supporting multiple transports.
Wrap refresh into a function.
Extract Tasseo object.

Includes the common code that should be the same with every transport.
Don't need to check for false metrics anymore.
Adding optional github auth
Update README
bind our click events
Merge pull request #34 from eric/github-auth

Github auth
Merge branch 'master' of github.com:obfuscurity/tasseo
use Graphite's native keepLastValue() as our null padding, refs #14
make padnulls a dashboard option, refs #35
document padnulls, refs #35
add support for hiding the toolbar

Allow a dashboard attribute 'toolbar' (true|false) that dictates
whether the toolbar should be shown.