* Upgrade to rails 5.1
- Update versions of dependencies
- Switch before_filter to before_action
- Use render plain rather than render text
* Generate new rails 5.1 scripts
Sphinx's searchd is very buggy, often crashing on rebuilding its
indexes, not starting up, or just spinning at 100% CPU.
It is also a big external dependency that might not be available on
other hosting platforms.
This removes the ability to search both comments and stories at
once, though I don't know how useful that was anyway. We gain
boolean searching and the ability to more carefully craft queries
using particular keywords (in the future) like "user:blah" or
"tag:blah" to narrow things down.
The previous version of `htmlentities` had a duplicate key in one of
its hashes, which produced the following warning:
```
.../htmlentities-4.3.2/lib/htmlentities/mappings/expanded.rb:465:
warning: key "inodot" is duplicated and overwritten on line 466
```
Updating to the latest removes this warning.
Judging from the test suite, the only issue in supporting Ruby 2.2.0+
was with the `mysql2` gem. Updating this to the latest 0.3.x allows
Lobsters to run with newer Rubies.
We can't update to the absolute latest `mysql2` gem without first
updating Rails, which is why I used the pessimistic version constraint
for `mysql2`.
