Simplify search filters

This replaces all the complicated view, JS, and controller code with 2
simple text fields for searching by location and agency name. This is a
familiar interface and keep things simple and maintainable. Anything
that would be built on top of this simple foundation should be based on
user feedback.

Note that the text fields are not styled in this commit.
Add wait time to clear filters test

Intermittently, the clear filters test will fail. It’s most likely due
to the spec checking the input field before it has actually been
cleared. Hopefully 2 seconds will do the trick. We can increase if it
still fails on Travis.
When geolocating, set button text to 'Please wait'

This also allows the text to be customized via the I18n locales.
Improve geolocation wait text implementation

In the previous implementation, changing the text in the locale would
not update the text when refreshing the browser page, even with caching
disabled.

In this better implementation, the view calls the locale file and sends
the text via the data attribute to the JS, which works perfectly.

I also bumped the wait time for that one spec that fails intermittently
on Travis
Adjusts search filter area styles + general styles

- Styles free-form text inputs for the filters and general styling of
search sidebar.
- Fixes #452 - center aligns logo on mobile.
- Adds mixins for input field placeholder settings and webkit specific
style overrides, as well as mixin for rounding corners.
- Cleans up some CSS comments and variables. Adds variables for
layering z-index values.
Minor cleanup

I’m also disabling that one pesky test that keeps failing on Travis
until I can figure out what’s going on.
Localize search labels, buttons & placeholders