do not write default empty sys.config or vm.args if it exists already
add lib_dirs option to for config file, same as -l cli arg
add -p for setting code paths
add rb16b01 and 02 and don't run dialyzer for r15 and below
fix deps target for shell target
add -v/--version cli option
Merge pull request #44 from tsloughter/master

allow template for sys.config and vm.args add lib_dirs config option