Handling of the "Release" Regex and -rc versions

[matthid]

Some minor changes are required to increase usability:

• The Task should maybe error out with a good error message if the Regex is not recognizing anything (the user can leave it blank to indicate that he doesn't want to use the feature)
• There might be an option to not add a slash after the rc, ie 0.11.3-rc4 or 0.11.3-rc.4 instead of 0.11.3-rc-4 (check the semver spec)