Implement command 'list' as a specialized 'query'

The 'git-gerrit list' command simply invokes 'git-gerrit query' with
two extra queries, simulating the standard queries used to create
Gerrit's "My Changes" dashboard.

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>
Fix option processing

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>