Calling callback in kml tests

Also reordering things so we have `expect(got).to.xmleql(expected)`.
Calling callback in GML v2 tests
Calling callback in GML v3 tests
Calling callback in WMS capabilities tests
Get rid of unnecessary `waitsFor` function

This was a relic from the Jasmine tests.  Mocha tests have a built-in timeout.  Async tests are registered with a function that takes a callback.
Merge pull request #810 from tschaub/async-tests

Proper async testing
Allow getMetersPerUnit to work without units identifier (see #814)
Use getMetersPer unit method
Reuse tile range
Merge pull request #814 from tschaub/814-min-resolution

Fix vector rendering for projections that do not specify units
Override for clarity
Fix doc bug
Less code

Since out meters per unit conversion table is a bit spare, prefer the configured conversion.
Merge pull request #815 from tschaub/override

Override for clarity
Use ol.Projection#.getMetersPerUnit()

As a follow-up to #815, this change makes
ol.tilegrid.createForProjection work in cases where a Proj4
projection does not have units set. For better code readability,
a new variable is used when calculating the resolution.
Merge pull request #816 from ahocevar/tilegrid-units

Use ol.Projection#getMetersPerUnit(). r=@tschaub
Pass options to the base class