use init instead of setBinding to initialize tool

previously tools used setBinding to initialize itself,
this seemed kind of weird.  MetridocScript has
supported init() for awhile.  Converting older tools
to use this instead
clean up the ParseArgsTest

per Thomas's note, cleaned up test
so ParseArgsTool is initialized how
it should be
Merge pull request #33 from metridoc/fix-init-on-tools

use init instead of setBinding to initialize tool