Code coverage shows test folder and not app

The whitelisting of the code coverage was set to only show the coverage of
the test folder itself; which unsurpisingly was almost 100%. By changing the
whitelist to point to the app folder in the root of the project we get an
accurate representation of the code coverage.

After running the unit tests one can see the code coverage in the
build/coverage folder; by opening the index.html you can browse through all
files and determine what needs to be covered.
Remove superfluous and misleading echo's

In the each call to render seems to be prefixed with the echo keyword
but the render method does not return data; it adds the rendered output
to the view cache / output buffer so that it can be echo'd later
by Slim itself.

In this commit I remove all superfluous echo's since it may mislead
people into thinking that the echo's actually have a function and use
it to circumvent the view mechanism of Slim or have unpredictable bugs.
Add Bootstrap 3.1.1
Add FontAwesome 4.1.0
Update jQuery to 2.1.1
Switch to using Bootstrap

- Now actually responsive!
- Adds sidebar
  - Login, takes you back to the same page
  - Splits to have event info on top of page, login below page
  - Combell logo disappears on mobile, as it's directly above the footer which also contains it
- Added a link to github in the footer (left)
- Nicer pager
- Clearer (actionable) "I will be attending"/"I attended" text+buttons
- Short URLs now have a "Copy to Clipboard" UI
  - uses flash but:
  - is hidden on mobile/tablet
  - will highlight the text in the input when focused, or clicked without flash
- Comments have a new interface
  - Supports gravatar
  - Comment shown above author/date/via
  - via is hidden on mobile
  - When ratings are shown they are also responsive:
    - Horizontal/on-top for desktop
    - Vertical/left for small/tablet
    - Vertical/on-top for mobile
- Twig will check for local images before linking to the old joind.in site
Strip down bootstrap to the essentials
Make the key responsive
Disable zoom
Add gulp to minify/concat JS/CSS
Add `watch` task
Revert "Disable zoom"

This reverts commit 85c73a25d3713384caf6dc4693c61f3dbbd812b0.

Conflicts:
	app/templates/layout.html.twig
Add a header to state files are generated
Fix bug in FF where it scrolls to the bottom
Switch to PNG images
Customize FontAwesome
Merge branch 'pr115'
Merge branch 'remove-echos-before-renders' of github.com:mvriel/joindin-web2 into pr116
Merge branch 'pr116'
Rework comments to use less space