README: Remove unnecessary dependencies.

Modify instructions for setting up development environment:
- remove version numbers from components where any version works
- remove components that are not needed
Add Lesson Three.

- Include guava-15.0.jar in libs/
- Configure integration with Google Play Services and Google Maps API v2
- Replace android-support-v13.jar with android-support-v4.jar, which
  is strangely enough the latest version of the support library.
- Use FragmentPagerAdapter instead of FragmentStatePagerAdapter to prevent
  crashes.