Added new Config value for libraries

This config value specifies the paths to required Android
Library projects (relative to the project base dir). When
present, it supercedes the libraries from project.properties.

Also added a few constants in AndroidManifest.java to replace
hard-coded strings.
Fixed NPE on StrictMode.setVmPolicy
Initialize ShadowImageView.matrix field to prevent NPE. Real android source starts with this field initialized:-

https://android.googlesource.com/platform/frameworks/base/+/jb-release/core/java/android/widget/ImageView.java
Add test for ImageView to show that ImageView.matrix must be initialized
Merge branch 'master' of https://github.com/robolectric/robolectric into shadow_image_view_fix
Implement Theme.applyStyle() correctly.

Existing implementation only sets (and overrides) previous theme styles. Correct behaviour should overlay styles of the original Theme replacing original attributes conditionally when "force" == true.
Add overlayed styles to the end of the list not the beginning, the ones added later are the ones that are applied last.
Initialize attr array as empty array when passed in as null.
Only look up style resource if it could be resolved.
Rework how overlayed styles are applied in Robolectric.

ShadowAssetManager should keep a list of overlayed styles, but rather than trying to process them in the theme we should do so in ShadowResources since we need to resolve each attribute and any possible references through indirection at this point.
Merge pull request #1271 from jongerrish/shadow_image_view_fix

Initialize ShadowImageView.matrix field to prevent NPE.
Support custom item states in android selectors.

This was failing because custom namespaced attributes are not correctly resolved, since the Node.getName()
returns the fully qualified name including the namespace which cannot be resolved in Robolectric's ResourceIndex.

We actually need to check here if the attribute's namespace is the default namespace and if so then we can just
return the local name.

This PR is also related to https://github.com/robolectric/robolectric/pull/1272 which will
replace any res-auto custom namespaces with the default package.
Add support for mipmaps in layouts.
Merge pull request #1281 from jongerrish/construct_custom_views_with_custom_state

Support custom item states in android selectors.
Fix bug with incorrect custom namespace from PR: https://github.com/robolectric/robolectric/pull/1281
Support for subclasses of android.content.res.Resources().

ShadowResources will use the application ResourceLoader by default. Only the System Resources will have its ResourceLoader explicitly bound.

Convert all references to resourceLoader instance member to using the accessor to ensure instantiation.

Add test which exposed an NPE for ShadowResources.resourceLoader and fix.
Merge branch 'master' of https://github.com/robolectric/robolectric into support_mipmap_resources
Merge pull request #1279 from jongerrish/shadow_resource_subclasses_should_have_app_resourceloader

Shadow resource subclasses should have app resourceloader.
Merge pull request #1286 from jongerrish/fix_custom_namespace_bug

Fix bug with incorrect custom namespace.
Fix incorrect assertion in the test. The change in this PR inadvertantly fixed a bug whereby invalid resources were being added to the map.
Merge branch 'master' of https://github.com/robolectric/robolectric into fix_theme_apply_style

Conflicts:
	src/test/java/org/robolectric/R.java
	src/test/java/org/robolectric/shadows/ResourcesTest.java