Update .travis.yml

Test to remove:
- ./travis-tool.sh github_package assertthat
ok
Stop base_url with bad API

With wrong api string the base_url return the url function from base. This fix will rise error if API is unknown.
Fix base_url example in interactive_pxweb sweSCB -> scb
Merge pull request #43 from jhuovari/master

Stop base_url with bad API
Update DESCRIPTION

Added error for missing api
Added swedish agricultural agency
Merge pull request #48 from rOpenGov/master

Update api_fix branch