pkgname url in api to restrictive

[Michael Vogt]

The urls for the pkgname are too restrictive currently, a packagename like "aclock.app" is valid but the re in both rnrclient and server do not allow that. From the debian policy:
http://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Source
"""
Package names (both source and binary, see Package, Section 5.6.7) must consist only of lower case letters (a-z), digits (0-9), plus (+) and minus (-) signs, and periods (.). They must be at least two characters long and must start with an alphanumeric character.
"""