Remove all references to unimplemented android folder
Issue #1 - Deactivate GPS updates on survey tab change

* When a geolocation question is registered to receive updates and
another tab is pressed, the GPS updates are no longer needed.
* 'Next' button and Tab explicit click flows are now merged.
* Keep track of current Tab index.
* Leave accuracy status as is, since the location is also kept. Only
'Searching' indicator is restored when the GPS updates are removed.
Add markdown extension to README file
Issue #9 - Optimize MD5 checksum algorithm for large files

* Use a byte buffer to update the MessageDiggest in blocks of 2048 bytes.
* Move MD5 checksum utility to FileUtil helper class.
Issue #9 - Fix InputStreamReader's read() value check
Issue #2 - Delete duplicate images from DCIM directory

* To avoid some camera applications' duplicate images, whenever the
image capture intent is returned, the MediaStore provider is checked to
ensure no duplications are found (most likely in the DCIM folder). If a
duplication is found, it will be deleted from the device.
Issue #13 - Search for lower case response headers to avoid HttpUrlConnection bug.

* Prior to Gingerbread, HttpUrlConnection converted all response
headers to lower case. This is a workaround to ensure we cover
those situations as well
Issue #11 - Use the checksum of the images as fallback

* If no datetime attribute is found in the exif, compute the MD5
checksum of both images to determine if they are the same.
Merge branch 'develop' into feature/deletedata
Issue #14 - Create a helper class to wrap formZip() response

* Define ZipFileData to hold zip file's metadata.
* Use interfaces for declarations. Classes for implementations.
Issue #14 - Split zip creation functionality

* Separate zip creation from data upload
* Use interfaces for declarations, classes for implementations
* Remove unused code
* Refactor long methods
Issue 14 - Handle Amazon S3 upload failure
Issue #14 - Add html to javadoc