Relax package version format checking when downloading from git-based urls

[tahalukmanji]

Some packages have a versioning system like -. and this may be due to the fact that their version starts from 0 and hence does not need to put a zero after the hyphen.

Example:

Traceback (most recent call last):
File "/usr/local/bin/pip2pi", line 11, in
sys.exit(pip2pi())
File "/usr/local/lib/python2.7/site-packages/libpip2pi/commands.py", line 510, in pip2pi
res = _dir2pi(option, subcmd_argv)
File "/usr/local/lib/python2.7/site-packages/libpip2pi/commands.py", line 290, in _dir2pi
pkg_name, pkg_rest = file_to_package(pkg_basename, pkgdir)
File "/usr/local/lib/python2.7/site-packages/libpip2pi/commands.py", line 123, in file_to_package
raise InvalidFilePackageName(file, basedir)
libpip2pi.commands.InvalidFilePackageName: unexpected file name: 'xfl-.06.zip' (not in 'pkg-name-version.xxx' format; found in directory: '/root/pypi_copy/var/www/packGeppers')