Replace assets with new ones

These are in the library project now since Gradle will merge asset
directories, and this allows for easier overriding of assets
Bring in AppCompat to support Holo style themes on older phones
Switch from using TabHost to using ActionBar

There is a lot of annoyance involved with this, since all of our tabs
have to be Fragments instead of Activities.

Notably:
 - Click handlers have to be wired up in Java, not XML
   (we could make this easier with something like Android Annotations)
 - When using a mpa inside a fragment you run into a bunch of issues.
   You must either you add a MapFragment in Java, and replace it every
   time the fragment is reloaded, or use a MapView directly and forward it
   all of the fragment's lifecycle events.
   Either way the map state is lost when the fragment is reloaded, so to
   prevent that we hide and show our tabs instead of attaching and
   detaching them to minimize fragment reloads.
 - You can't dynamically change the view using setContentView, like
   the ProfileDisplay activity was doing
 - You have to do cleanup when adding Views to a fragment dynamically,
   because the fragment may get detached and reused.
Add generated Holo style overrides

Files were generated using http://android-holo-colors.com/ and
http://jgilfelt.github.io/android-actionbarstylegenerator

All of the themes_holo_custom.xml files were then manually edited to make
@style/holo_custom inherit from @style/Theme.Actionbar_custom and to
change android:textColorHighlight to use @color/primaryColor
Merge pull request #76 from maurizi/mapActivityFragmented

Add new image assets and override Holo themes
Ensure assets folder always exists