Added first (incomplete) implementation of `--only` command
Implemented matcher(s)
Include the new command
This command is InstanceAble and Reader
Fixed merge if time is nil
Ensure we return if nil is passed, added debugging and changed #parse call a bit
Added more debugging output and splitted code to be more readable
Fix: We must be able to check a partitial path, such as "foo/bar/2014", so we must be able to check for single path elements from the date/time spec
Check responsibility first, then check if path contains pattern
Fixup: Dont check date two times, check time!
Added regex override
Rewrote path matching

This patch rewrites the complete path matching.

The new version builds the regex for the path and checks it after each
build step. The File part is build after that, if the path matching was
not successfull.

The File part can be build in one step, as the path gets only longer by
one element: The filename.
Fixed argument parsing

The problem was that we blindly parsed the argument string (for example)
with Time.strptime, which was not good, as if the string is "12:13", so
the second is missing, the Time.strptime assumes the second to be "00".
We don't want that behaviour, so I added a workaround which remembers
which keys are parsed and sets them in the result hash only if they were
parsed.
Refactored key setting into helper method
Remove outdated method and use #t_or_regex method
Removed blank line
Shortened regex building a bit
Merge branch 'add-only_command'