(GH-58) [module/svn] Add svn module skeleton
[execution] Pass #execute options to systemu invocation

This allows callers to pass things through like :cwd.
(GH-58) [module/svn] Build out basic status checks
[module/svn] svn status should check URL and revision
[module/svn] Test coverage for installing svn modules
[module/svn] Allow svn modules to be reinstalled/updated
[module/svn] Add SVN as a real module type
[module/svn] Run `svn checkout` in correct directory
[spec/system] Extract provisioning steps to mixin
[module/svn] Add system test coverage
(GH-58) Install module with specific revision
(GH-58) Only update to revision if there is a revision.
[svn/working_dir] Correct arguments passed to svn exec command
[module/svn] Add more system spec coverage
[spec/system] Extract module cleanup steps
[spec/system] reorganize svn acceptance tests
(maint) Fix svn unit tests to match working behavior
Merge branch 'feature/next/gh-58/svn-module-provider' into next