Remove output file.
Add --skip option to command-line parser.

This is used in code, but not parsed from the command-line.
Remove equals signs from short options.

They're stripped by optparse anyway and don't actually work if you try
to use them with the short names. They're optional with the long names
(on the command-line). Also, fix description of default directory.
Fix test for command success.
Exit 99 when no tests exist in specified directory.

Certainly, no tests existing should not exit without an error. The
reason for choosing 99 is that automake treats that as a "hard" error.
Remove unnecessary quoting.

Since apparently quotes don't care about newlines in Ruby, it's much
clearer to not have the newline escapes and concatenated strings.
Make spec directory into a non-switch argument.
Add tests on null values

Add tests with null values stored in variables
Merge pull request #4 from Nabellaleen/libsassNullValues

Add tests on null values
Merge pull request #2 from QuLogic/master

Fix some cli issues.