Many changes see details

Done:
- Added WifiRecord and changed WifiMarker according to issue posted on
July 19th.
- OfflineWifiDB -> OfflineBuffer; push() operation now checks if
WifiConnection should be pushed based on when the last update was.
- Extracted serialize() and deserialize() from WifiConnection to
OfflineBuffer.
- Added a new column to OfflineBuffer's database for update time.
- WifiConnection should now properly support serialization.
- Moved ServerConnection and ServerConnectionFailureException to
com.napontaratan.wifi.server.
- Better encapsulation within ServerConnection. Retrieving WifiMarker
now done with a single call to getWifiMarker().
- Extracted some methods and tasks from MapActivity to WifiController.
- Minor name changes in many places.
- Replaced literals with constants in many places.

To Do:
- Create separate classes for wifi database server connection and
geocode server connection.
- Update server scripts to reflect client-side changes.
- Consider a different URL encoding scheme.
- Implement a way to interpret ScanResult.capabilities to determine if
connection is secured.
- Improve OfflineBuffer.shouldPush().
- Allow application to scan for wifi connections more frequently
(currently runs only once upon start).
Conflict Resolution

Conflicts:
	src/com/napontaratan/wifi/server/ServerConnection.java
	src/com/napontaratan/wifi/view/MapActivity.java