Update manifest for 2.4.1.

Rev the versionCode to 14 and versionName to 2.4.1.

Make having a rear-facing camera optional. Hopefully this will let Nexus 7 users see the app on the Play Store.
reduced the number of build errors by removing unused imports, parameterizing generic types
reduce the number of build warnings by parameterizing generic types
* use the mdpi screen density for drawing the map details photo
* this fixes #3
Revert "* use the mdpi screen density for drawing the map details photo"

This reverts commit 8137afbe8088d1c37745211f30fb552e8bd7f305.
Merge branch 'master' into 2.4-dev
* use the mdpi screen density for drawing the map details photo
* this fixes #3
issue #6
* a very minor code tweak, so it takes less codes to initialize the pull-to-refresh menu
* add pull-to-refresh to three screens of the shuttles module
make sure pull-to-refresh behaves properly when fetching list of routes fails
reduced the number of build warings
modified RoutesAsyncListView to use alternate pull to refresh code from https://github.com/johannilsson/android-pulltorefresh and fix the stack overflow errors on certain android devices
added git submodule android-pulltorefresh
Revert "added git submodule android-pulltorefresh"

This reverts commit 01ce55e01ec91fde1af2921411a13066bb03be75.
Revert "modified RoutesAsyncListView to use alternate pull to refresh code from https://github.com/johannilsson/android-pulltorefresh and fix the stack overflow errors on certain android devices"

This reverts commit f580fb9e4db6a56975dc2aabc8793e285cbd05c2.
* use fixes for ActionBar-PullToRefresh
* simple sublcass of ScrollView that allows the pull-to-refresh
  handling to trigger even when the content is too short to need scrolling.
* use pull-to-refresh for emergency module.
* use special ScrollView subclass for refreshable content in dining.
* actually use the constant, meant to define the minimum the user has to scroll
  before we start to override the ScrollViews natural behavior.