Several updates for TCIA Browser

Updates:
- Reorganized code and putting parts of code in helper classes in TCIABrowserLin
- Added option to cache query results to local disk for faster operation.
- Added option to combine clinical data from http://www.cbioportal.org/
- UI redesign and update.

Compare link: https://github.com/QIICR/TCIABrowser/compare/db7cd25...75d621