Make Shadows package configurable.
Add asset directory configuration to Config annotation.

Fixes #1214.
Merge pull request #1387 from erd/config-assets-directory

Add asset directory configuration to Config annotation.
Merge pull request #1391 from kriegfrj/configure-shadows-package

Make Shadows package configurable
Support android 4.4.
Add webviewchromium build target for KitKat.
Move shadows into robolectric-shadows module.
Rename and repackage methods in MagicObject and ShadowThingy.
Rename robolectric-res to robolectric-resources.
Run annotation processor on generated shadows.

Inline shadowOf_ and replace some calls with generated shadowOf methods.
Update asset/resource resolution

Make asset and resource path resolution consistent with manifest
resolution. Use system property values before default values.

This allows merged assets and resources paths to be specified in system
properties the same way the AndroidManifest.xml path is specified.
Merge pull request #1400 from jle/split-res-asset-resolution-from-manifest

Update asset/resource resolution
Extract robolectric-fakehttp.
Hide references to robolectric-shadows inside of ShadowsAdapter.
Inline Robolectric methods that use ShadowLooper.
Extract FakeHttp from Robolectric, and put it in robolectric-shadows.
Move methods out of Robolectric that belong in robolectric-shadows.
Extract ShadowsAdapter interface from Api18ShadowsAdapter.
Hide references to robolectric-shadows inside of ShadowsAdapter.
Remove robolectric's compile-time dependency on robolectric-shadows.