make bin/traceur.js bin/traceur-runtime.js

Changes include:
1. Using ant task (instead of wagon) to download archive from git,
2. Using make (and npm, indirectly) to build traceur.js and traceur-runtime.js,
3. Tabs instead of spaces for indentation.

Sorry for 3rd, I used auto format and forgot about it.

I realize that building jar is now more system dependent (npm), however it seems to be a price worth paying. I believe that having compiled code is much more useful than just having sources.