Fix regression in DataSourceCollection.removeAll.

Add spec to make sure that removeAll actually removes all data sources.  Fixes #1772
Merge pull request #1773 from AnalyticalGraphicsInc/fixDataSourceCollectionRemoveAll

Fix regression in DataSourceCollection.removeAll.
Test workarounds for IE 11
Improve reference doc for options parameters
Bump version.
Getter doc fix
Include VERSION property in Cesium object.
Merge pull request #1779 from AnalyticalGraphicsInc/version

Include VERSION property in Cesium object.
Merge pull request #1776 from AnalyticalGraphicsInc/ie11-premultiplied

More test workarounds for IE 11
Merge pull request #1777 from AnalyticalGraphicsInc/options

Improve reference doc for options parameters
Merge pull request #1778 from AnalyticalGraphicsInc/type

Use type' instead' of 'return' for getters
Merge remote-tracking branch 'origin/master' into projection