Check for presence of divefile and load it

If the file with given name is already present, load the file to subsurface code
first. Then download new dives and process and save old/new dives as per the
options provided. (Prefer/Force) checkboxes.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>
Added about page

This page contains information about the project, developer, mentor and
organisation as well as project repo and developer email address.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>
Changed icon, updated name and navigation

Home as up enabled in settings.
Name changed to Subsurface Android Downloader
Icon changed to subsurface icon.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>
Update subsurface commit to include androidhelper.

Signed-off-by: Venkatesh Shukla <venkatesh.shukla.eee11@iitbhu.ac.in>