Remove all submodule usage

Use node packages instead of git submodules for the developer
dependencies.
This means using the Leaflet npm module and not using leaflet-tilejson
anymore.
This patch, by incident, also fixes all examples to explicitly load the
zoomslider since it doesn't load automatically anymore since 0.6.2.
Remove old dependencies

Remove jake (since we use grunt now) and uglify-js (since we don't use
that at all).
Fix tests

Commit 165d334 made the zoom control not load automatically
anymore. This commit updates the tests accordingly.
Move to the grunt-karma task

Use the grunt karma task instead of our own hand rolled one.
Update Leaflet dependency

Update Leaflet to 0.7.1
WIP Update styles for 0.7.1

Leaflet 0.7.x doesn't use specific styles for IE anymore and also drops
support for IE6. This commits does the same for us.
Bump version

Bump version to 0.7.0
Make example test2 work in old IE

Make a conditional check for console.log in test2.html