Pin bower dependencies, add JS source maps, fix AJAX endpoints

[contolini]

I'm going to work off a new rram branch until I'm confident I'm not breaking anything.

The main change here is the location of some vendor assets. The leaflet utfgrid and minimap plugins changed their directory structures causing the grunt CSS and JS tasks to fail. I updated the paths in the gruntfile and pinned the dependencies in bower.json so that they can't change in the future.

Changes

• Change grunt-uglify's compress option to {} See TypeError: Cannot assign to read only property 'warnings' of true gruntjs/grunt-contrib-uglify#298.
• Pinned bower dependencies.
• Updated paths to vendor JS and CSS files.
• Only create source maps if we're in Jenkins or Travis. (I'm not confident this makes sense given that built JS assets are being tracked in git. Is this a pointless change?).
• Add slashes to API endpoints to circumvent weird redirect error.

Review

• @sephcoster
• @mehtadev17

cc @sleitner

[sephcoster]

Updated dependencies look good. 👍