Rescue malformed JSON config

Since we cannot parse the repo configuration, return an empty hash, as if the
was no configuration at all.
Upgrade to ruby 2.1.3
Revise setup instructions in README.md

* Set up local environment and clarified instructions in `README.md`
* Centralize on localhost:5000, since that's the default Foreman port
* Clearer GitHub and Stripe instructions

https://trello.com/c/TpFwhtlt/333-replicate-setup-locally-and-update-readme-me
Force UTF-8 encoding on file contents

`Base64.decode64` returns a string with encoding of `ASCII-8BIT`. Some linters
will try to write the file. If a file contains weird characters, an error will
get raised, like:

```
 Encoding::UndefinedConversionError: "\xE2" from ASCII-8BIT to UTF-8
```

Related error:
https://app.getsentry.com/app20126465herokucom/production/group/33706905/
Fix exemption check

* Check failed when more than one org was added. This change fixes that.
Configure Redis using redis-db defaults

* This commit implements a change suggested by @lunks in
  https://github.com/thoughtbot/hound/issues/444
* Remove Redis configuration in favor of redis-db's default configuration
* Reference: https://github.com/redis/redis-rb#getting-started
* Remove references to `REDISTOGO_URL` environment variable
* Note: Prior to merging and deploying this commit a `REDIS_URL`
  environment variable should be set on Heroku
* https://trello.com/c/AlmhdrFd/399-change-redistogo-url-environment-variable-to-redis-url
Start a FAQ page

* Add a HighVoltage page at `/faq`
* Link to FAQ on landing page
* Add a link to the footer of the landing page
* Override HighVoltage's `PagesController` to skip authentication and be public
* Use double quotes

Minor:
* Move styles for anchor tags from `_base` into the more specific `_header` where it used

https://trello.com/c/h9zfaC9l/386-add-an-faq
Add SECURITY.md document, linked from footer

* Move all similar docs to `doc/` directory.
Document sync'ing and enabling repos
Payment
Stubs for remaining sections
Third-party auditing
Remove AVAIALBILITY doc for now