Use a submodule for openlayers

This is to work around a problem in ol3: https://github.com/openlayers/ol3/issues/2668. When the problem is fixed we will need to decide how we want to install ol3 in ngeo, with npm or as a submodule.
Merge pull request #40 from elemoine/openlayers

Use a submodule for openlayers
Fix a bug in Makefile
Use new compiler options
Update closure-library version

Same version as ol3
Set es5Strict check as error
Merge pull request #41 from elemoine/makefile

Fix a bug in Makefile
Merge pull request #39 from fredj/compiler-options

Use new compiler options
Fix minor typo in interactionbtngroup example
Merge pull request #43 from fredj/typo

Fix minor typo in interactionbtngroup example
Update AngularJS to 1.3.0-rc.0
Merge pull request #45 from fredj/update-angular

Update AngularJS to 1.3.0-rc.0
Revert "Use a submodule for openlayers"

This reverts commit df9a7bb72a0ef3311b9d808c90ea7ed301957fdb.
Rely on OpenLayers' closure-util dependency
Merge pull request #46 from elemoine/openlayers

Remove closure-util as a direct dependency
Add compilation levels : simple & whitespace
use new compiler options (related to #39)