Removed not needed query files

Added new query files that deal with obtaining cohort information: get_study_cohorts.sql and get_study_cohorts.query.xml

HAI_vs_GE.Rmd : modified code to make a parameter name more specific

begin.html :
- moved script fetching to the end to speed up loading

HAI_vs_GE.js :
- added a store that relies on the added query (see above)
- added a combo box that uses the data of the store above
- modified code to make a parameter name more specific
- changed the parameters panel layout type to 'form'