Add support for explicit type specifiers when calling git-repo-config

Add support for explicit type specifiers when calling git-repo-config

Currently, git-repo-config will just return the raw value of option
as specified in the config file; this makes things difficult for scripts
calling it, especially if the value is supposed to be boolean.

This patch makes it possible to ask git-repo-config to check if the option
is of the given type (int or bool) and write out the value in its
canonical form. If you do not pass --int or --bool, the behaviour stays
unchanged and the raw value is emitted.

This also incidentally fixes the segfault when option with no value is
encountered.

[jc: tweaked the option parsing a bit to make it easier to see
 that the patch does not change anything but the type stuff in
 the diff output.  Also changed to avoid "foo ? : bar" construct. ]

Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Junio C Hamano <junkio@cox.net>