Kwd search without autocompletion

this pull is mostly focusing on integration of KWS into DAS. some features will be improved if time allows. 

*src/python/DAS/web/das_web_srv.py*: 
- renders src/templates/kwdsearch_via_ajax.tmpl within das_ambigous. The earlier loads keyword search results via ajax from same or different server.
- when loading the results, uses src/python/DAS/web/cms_query_rewrite.py to check if query has filters on missing fields. if so checks if these can be retrieved through nested subquery on PK. 
  * this is quite important for keyword search to filter properly as otherwise it would be harder to guarantee that suggestions are correct.
  * still last changes to das/services seem to stabilize the fields available for different types of queries

Recent changes:
- Kwdsearch web part was modified to remove dependencies from jquery. switched to http://www.opentip.org/ which seem to be quite solid.
- currently we use simple whitelist of rules for cases when wildcards are allowed. may be worth moving to DB of service mappings but I would not hurry.  https://github.com/vidma/DAS/compare/kwd-search-clean-no-autocompl#L40R236

DAS.keywordsearch package is still of variable quality:
- keywordsearch/rankers/fast_recursive_ranker.c is automatically generated by cython from corresponding .pyx/pxd
  * scoring shall be fixed/improved. some parts need cleanup.
- keywordsearch/rankers/simple_recursive_ranker.py *is rubish but works, don't read it (it's replaced by cython version "fast_recursive_ranker"; so far left it to be able to compare with the newer)*
tests/
*   there are 7 tests which are intentionally left to fail. the ranker shall still be improved slightly...

The current version is installed on https://das-test-dbs2.cern.ch/das/