CheckFile: improve error messages
CheckFile: replace temp filename with real name in command output

The output from the external commands may refer to the filename which
they were called to check. Since the actual file is a temporary its name
will confound the user. So, we replace any mention of the temporary
filename in the output with the name of the file in the repository.
CheckJira: Invert some checks

The order of checks is changed from (unresolved > status > issuetype)
to (issuetype > status > unresolved) so that it goes from the more
general to the more specific.

This also changes some of the error messages.
Add global $Git::More::CONFIG_ENCODING

This global variable tells get_config which encoding is used in Git's
configuration files so that it can decode them appropriately.
Normalize branch names gotten from Gerrit

When Gerrit mentions a branch name via the hooks arguments it uses the
branch short-name if it is in the refs/heads/ namespace. But we need to
normalize on the long-name, so we detect short-names and convert them
into long-names here.
CheckJira: tell the user which issuetypes and statuses are approved