Use parsable task --version instead of internal task _version which may be a git ref

[synrg]

When task is installed directly from git instead of from a released tarball, the internal 'task _version' reports the git ref of HEAD. This causes Versionomy.parse to choke, as it does not conform to any recognizable version numbering scheme, and besides which, even if it did not crash, a git ref would not be comparable with '1.9.2'.

Please apply the patch at https://gist.github.com/synrg/6408282 which fixes this issue.