piston improvements. adds version endpoint, new execution output, awk language support, and installs all dependencies directly when possible and avoids apt unless not possible

tests/test.awk

@@ -0,0 +1,3 @@
+good
+___code___
+{ print }

tests/test_all_lxc

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+echo 'testing awk'
+../lxc/execute awk test.awk
 echo 'testing c'
 ../lxc/execute c test.c
 echo 'testing cpp'