Search correctly weights parts of search documents

The search will now rank results correctly based on how they are
weighted in the materialized view.
Merge pull request #49 from unepwcmc/fix-search

Search correctly weights parts of search documents
Correct use of ansible variables for memcache template
Fixes memcache ansible tasks

Default task files must be called main.yml
Improves provisioning scripts for different server roles

Previously all servers ran the same scripts and had the same setup. This
commit changes the scripts so that only the database server exposes a
postgres port, and only the web server installs nginx. This improves
security a little bit, but primarily just makes managing the servers
easier.
Correct user for ansible scripts
Adds instructions about handling GEOS issues in development on linux
Adds instructions on how to use ansible vault
Removes testing group var file
Correct ansible commands for provisioning

Stages now have separate inventory files so that they can be run
separately
Use correct inventory name for db config
Use correct psql flag for running commands non-interactively
Update ansible docs with correct host filenames
Update cleanup info in WDPA readme
Update servers provisioning docs after merging the ansible group vars
Add Slack travis integration
Merge pull request #50 from unepwcmc/ansible-db-servers

Ansible sets up DB servers correctly
Shapefile download generator returns immediately if no WDPA IDs are
given
Download generator no longer attempts to upload to S3 if now download is
generated (due to no WDPA IDs given)
Update cartodb layer for july