ENH: restructuring and new functionality for TCIA summary reporting

* reorganize the code to keep TCIAClient in a separate library to facilitate reuse outside Slicer
* added script to query all available series and save in a file for subsequent analysis
ENH: include additional attributes to be reported
BUG: remove missed merge conflict annotations
BUG: fix instantiation of TCIAClient
Merge pull request #19 from fedorov/stats-script

Code reorganization and TCIA summary script