plowdown, plowprobe: fix, incorrectly identified binary file

Credits go to Matthew Stanfield.
Fixes issue 1170.
plowdown, plowup: add --cache switch

revision f3130ecf495d7ab926d49b73d90404a07950c8ce
introduced module storage space.

There are three possible values:
- none
- session (default)
- shared

See man pages for documentation.
rapidgator (login): Handle rare 'heavy usage' issues

These can be:
- Enforced wait time before the login
- A custom Rapidgator Captcha (not the usual Solvemedia one)

See also issue 1105
plowdown: add log_notice message for unused command line option(s)

Might be useful!
keep2share (upload): check for expired token
Merge changes from debian mentoring
Merge branch 'upstream/master' into ubuntu/trusty
Add changelog from git log
Use ubuntu lintian profile
Correct new typos in man pages
Add description to patch