Add new function

Ask for user input (command for run).
If custom command is empty - run default (ls -la) command.
Change what cgchoffman ask

Return space on line 26.
Remade "command" condition (remove "else", not needed).
Oneline condition style

Oops, forgot that I must create a one-line condition :)
remove some brackets

I'm stupid :D
Brackets on line 34 not need :)
Merge pull request #4 from Defman21/patch-1

Thanks defman21!