Added bugtracker to the spec and schema

For #114
Merge remote-tracking branch 'origin/master' into 114_bugtracker

* origin/master: (44 commits)
  Document magic numbers in Linux detection.
  Documented what flipping enabled does in the Main GUI class.
  TransactionalFilesystem: Documented possible bug.
  Moved NetAsyncDownloader to its own file.
  ModuleInstaller: TODO: Break this into smaller pieces.
  ModuleInstaller: Documented inter-thread communication
  Module has consistent To/From Json/File methods.
  CmdLine: Add back `--kspdir` option.
  RegistryManager.Instance() now always requires a path.
  Cmdline: Remove now obsoleted 'config' option.
  Provide a stack backtrace in the GUI before calling Debugger.Break()
  GUI: Check our KSP install hasn't been set on the command-line.
  Not finding a gamedir when expect is no longer a fatal warning.
  Major overhaul of multi-instance KSP
  Accessing .Instances always makes sure it's loaded now.
  Populated GameData in test dir to make git happy.
  Added tests for IsKspDir() and test data.
  Test framework organisation overhaul.
  Fix verson detection and validation of KSP gamedir
  TODO: Less steps in cmdline for new instance setup.
  ...
Added resources.bugtracker to CKAN.Module.

- Added `bugtracker` resource
- Flipped homepage to Uri
- Flipped github.url to Uri
- Added tests.

Includes #135.
Closes #114.
Merge pull request #148 from pjf/114_bugtracker

Added resources.bugtracker to CKAN.Module.