Updates map marker graphics file

Updates map marker graphics file:
- Uses slices instead of artboards, because (a) slices stick to the
pixel grid, (b) number of slices has no cap, and (c) slices can export
all graphics at once.
- Adds instruction text to file.
- Adds filetype to readme.
- Removes unused swatches
- Adds default color swatch group for map markers.
Merge pull request #556 from codeforamerica/graphics-file-layer-names

Updates map marker graphics file
Removes excess padding in function call

Removes excess padding in function call to make this consistent with
formatting in smc-connect.
Refactors map to use marker manager

- Moves map icon management to its own module.
- Update marker icons to be more consistent with forks that have
differentiated map markers.
Updates contribution guidelines

Updates contribution guidelines:
- Consolidates/organizes ways to contribute section.
- Organizes bug report section.
- Adds hack request section.
Use Marshal serializer for faraday_http_cache

The default JSON serializer was causing an exception on certain pages. Marshal seems to fix the issue.
Update Ruby to 2.1.2 and ohanakapa to 1.1.2

With the update to ohanakapa 1.1.2, we no longer need to rescue the URITemplate error. Adding a quote to the end of a location URL will now just raise Ohanakapa::NotFound.
Merge pull request #558 from codeforamerica/add-hackrequest-link

Updates contribution guidelines
Bump Ruby version to 2.1.2 for Travis.
Updates stack versions in readme

Updates Ruby & Rails stack versions in readme to latest used versions.
Update compass-rails to 2.0.0

- Updates compass-rails to 2.0.0
- Updates compass to 0.12.7
Merge pull request #557 from codeforamerica/map-manager-refactor

Refactors map to use marker manager
Merge pull request #559 from codeforamerica/update-readme-stack

Updates stack versions in readme
Merge pull request #560 from codeforamerica/update-compass

Update compass-rails to 2.0.0
Updates map marker filename

Changes underscore to hyphen to be consistent with file naming
convention in other modules.
Adds applicationjs to all routes

application.js was excluded from the result and detail view routes.
This adds it to all route modules.
Merge pull request #563 from codeforamerica/applicationjs-all-routes

Adds applicationjs to all routes
Update default location text. Closes #554.
Merge pull request #566 from codeforamerica/554-default-location-text

Update default location text. Closes #554.
Adds right-hand padding on text input filters

Fixes #562 - adds right-hand padding on text input filters.