Massive sync as we move off mercurial internally

Moving forward changes will be in git both internally and externally, so
the commits will just match. Unfortunately for this particular commit
that bridges our hg to git move, it's a huge combined changeset. I do
apologize for that, it's not at all awesome.

For this sync there was lots of cleanup and some non-trivial features:
- Elastic monitoring is now using StackExchange's internal client that's
bare metal and only for the pieces of elastic we're using internally,
NEST has been removed
- Redis is now monitored via StackExchange.Redis, Booksleeve has been
removed.
- Redis nodes can now be slaved or promoted in the UI
- Redis client connections can now be killed in the UI
- Redis versions are now seen in the all-servers dashboard
- Redis slaves now indicate how far behind they are in replication
- Backoffs for errors are now overrideable per type (this will be
expanded a bit later)
- Exceptions (via StackExchange.Exceptional) got a performance overhaul
- Exceptions are now loaded as you scroll - this drastically increases
client render performance for large logs
- Sorting is now server-side, again for client performance around large
tables
- Exceptions table is now a bit leaner, e.g. "Exception" is trimmed from
the end of the type, etc.
- CloudFlare Dashboard added: Includes zones, DNS, and minimal railgun
statistics (pending v5 railgun release for being pretty)
- This will be ported to APIv4 in the near future (v4 was released only
yesterday)
- All polling actions can now be profiled, their profiles are available
for viewing in /about/caches
- This is done via MiniProfiler, any underlying systems that are aware
like redis and SQL and already hooked up
- ASP.Net MVC
- Now on version 5.2
- Views reworked to have the proper master/child relationships ASP.Net
MVC is designed for
- Library upgrades
- ASP.Net MVC from 4.3.0.30506 to 5.2.0
- Razor from 2.0.30506 to 3.2.0
- Web.Optimization from 1.1.0 to 1.1.3
- WebPages from 2.0.30506 to 3.2.0
- MiniProfiler from 3.0.8.55 to 3.1.1.139
- MiniProfiler.Mvc from 4.3.0.8.55 to 4.3.0.11.121
- Dapper from 1.13 to 1.25
- BookSleeve 1.3.41 to StackExchange.Redis 1.0.322
- NEST 0.20 fork to StackExchange.Elastic 0.1.25
- Jil for serialization in StackExchange.Elastic
- Sigil, the base of Jil
- Newtonsoft 5.0.8 to 6.0.3
- StackExchange.Exceptional 1.0.86 to 1.0.110
- WebGrease 1.1.0 to 1.6.0