Move to `string match` syntax from `grep` caused test to see if the Atom Package Manager is installed to always fail. This appears to fix the issue (tested on fish 2.3.0 with apm 1.6.0).
I believe apm must have been buggy - example output that I found online
showed `tr` was mangling paths with spaces in it. Should be fixed.
Also, use dscl on OS X in __fish_complete_users.fish like
__fish_print_users.fish already does.
`__fish_apm_using_command` was incorrectly taking lists of commands, new function added to support multiple a command having synonyms.
Simplify switch statement
Also remove superfluous function.
Allow for multiple completions after a command
Useful for removing packages, will complete for more than one.
Code improvements
