first stab at a common functions library. include argument parsing and a few definitions wired up. closes #932. closes #945

tests/unit/client.bats

@@ -21,7 +21,7 @@ teardown() {
 }
 
 @test "dokku client (no args should print help)" {
-  run /bin/bash -c "./contrib/dokku_client.sh | head -1 | grep -q 'dokku COMMAND <app>'"
+  run /bin/bash -c "./contrib/dokku_client.sh | head -1 | egrep -q '^Usage: dokku \[.+\] COMMAND <app>.*'"
   echo "output: "$output
   echo "status: "$status
   assert_success