Add support for adding tor version to the bridge_reachability report.

Fail with a good error code if the version is unsupported for the given bridge.
Use the correct version to check compatibility with scramblesuit
Provide a useful error message if we fail to load the inputfile
Iteration based on feedback from asn.

* Check that tor is installed before running the test (adding of new API method
  requirements used for doing checks before a test runs).
* Add description to bridge_reachability test.
* Consider the config.advanced.tor_binary option when running tor.
* Add command line option -v for extra verbosity (equivalent to debug: true)
Refactoring of .gitignore
Also print out the Tor version and print error messages.
Only print out a summary when it's appropriate.

Replace prints with log.msg
When we fail write the tor log to the report
Add support for fteproxy to bridge_reachability
Add support for installing fteproxy to install_on_planetlab script
Correct managed to --managed
Don't complain if we fail to delete some files.
Don't set requirements attribute since it's now used for another purpose.
Merge pull request #297 from TheTorProject/feature/tor_version

Add support for adding tor version to the bridge_reachability report.