#920 - add Lease<T> API; currently only {String|Hash}GetLease[Async] implemented; includes convenience methods for decoding or treating as a MemoryStream

# Conflicts:
#	src/StackExchange.Redis/Interfaces/IDatabase.cs
#	src/StackExchange.Redis/Interfaces/IDatabaseAsync.cs
#	src/StackExchange.Redis/RedisDatabase.cs

* Get multiple elements with SetPop

* Adjust names

This reverts commit 61f9c3a8.

Still needs fixing, but sanity checking this is the issue with some subscription tests. The flags change is a bit more invovled, not sure whether to switch to Message passing, or add Flags usages in some cases.

This moves to our normal directory layout, and removes the unused ConnectionWatcher.

Note 1: There's an apparently unused StackExchange.Redis.Modules I'm not sure about....going to let Marc nuke it if sure.

Note 2: the sentinel redis configs which are usually redis ignored may have absolute paths in them that need a quick update to get going again in a killall-> change config -> ./start-all.sh

cc @mgravell on above ^

Note: this doesn't include command and key, which is still behind the IncludeDetailInExceptions flag

I HATE this, but it's now just plain broken, and no one's going to fix it (or accept a fix for it).

Some socket fixes are in here...let's make sure we're getting them.

We're getting an extra in prod...need to figure out what it is. I'm betting a heartbeat in there.