Fixed readAll and writeAll for linux to allow multiple calls by creating a new command for each run. Added check for xsel binary in PATH, and added support to use xclip if xsel is not found.
Fixed readAll and writeAll for OSX to allow multiple calls to be completed in a run.
Updated README to with a new linux command that can be used

Added xclip as an option to be used on linux
Merge pull request #2 from JustinJudd/master

Fixed Command calls for readAll and writeAll to allow multiple runs. Also added additional Linux support