(maint) Add invalid version number to error msg

Prior to this commit the error message for invalid versions did not
return the version number. This commit adds the invalid version number
to the message.
Merge branch 'master' of git://github.com/grimradical/clj-semver into maint/0.1.0/add_invalid_version_info_to_error_message
Add a necessary space to error message
Merge pull request #2 from ajroetker/maint/0.1.0/add_invalid_version_info_to_error_message

(maint) Add invalid version number to error msg