Client: now saves in Android and getting Context in other classes

Added:
AbstractServer - Framework used in Client/Server
ConnectionToClient - Framework used in Client/Server
ApplicationContext - Allows us to get Context of Android application in
other java files.

Modified:
Client: Storing and Retrieving data store of past 5 transactions should
now work with Android file system.
Android Manafest: Modified in order for ApplicationContext to function
correctly