Fix -a option wrong concatenation of arguments.

[Aire-One]

The -a option handling in the code does not match what the documentation says.
From the --help output :

-a|--aopt Pass option to awesome binary (e.g. --no-argb or --check). Can be repeated.

But using multiple -a does not provide the expected result. If you run awmtt start -a --version -a --check the awesome binary will receive --version--check instead of --version --check (note the extra space).

Another solution, and probably the easiest, is to use quotes to wrap your arguments list. awmtt start -a '--version --check' ¯\(ツ)/¯