(CDAP-369) Fix cdap-cli

* CLI now reads cdap-site.xml in the classpath for hostname/port/ssl configuration
* CLI now saves the generated access token to the local filesystem for later use
* cdap-cli.bat now passes arguments through to `CLIMain`
* cdap-cli.sh now passes arguments through to `CLIMain` and no longer `cd`'s into the CLI jar's directory 

Tested on Windows and Mac.
It is ok to delete this if you made sure that no other tool depends on this. It seems that tx-debugger relies on it. But that is a tool that is hopefully rarely used, and I believe that one can pass in a token file name. Can you make sure that tx-debugger can read the token file generated by the cli?