ExtensionMethods.ToCredentialsFromUri would always return null

The method ExtensionMethods.ToCredentialsFromUri would always return
null because it was telling string.Split to only return 1 value.

Once that bug was fixed, it would cause units tests to fail because the
IChangeTrackerClient (specifically Puller) would not always have an
HttpClient.  Added an additional null check to ChangeTracker.
Changed to get compiling locally.
Synced with upstream master
Fixed incorrect cast.

revpos is an int, not a long.  Previously, it would cause a exception
when it tried to cast it to a long.
Merge branch 'master' of https://github.com/jonlipsky/couchbase-lite-net

Conflicts:
	src/Couchbase.Lite.Shared/Replication/ChangeTracker.cs
Removing "Release Notes" reference

The Release Notes for Xamarin are a built-in feature of the component dashboard page. Removing the Release Notes reference in the Details.md to avoid confusion.
Merge branch 'master' of https://github.com/jonlipsky/couchbase-lite-net
Fixed merge issue.
Fixed cast exception
Merge branch 'master' of https://github.com/jonlipsky/couchbase-lite-net
More fixes.
Merge branch 'master' of https://github.com/jonlipsky/couchbase-lite-net
Fixed another casting issue.
Merge branch 'master' of https://github.com/jonlipsky/couchbase-lite-net
Merge branch 'master' of https://github.com/couchbaselabs/couchbase-lite-net

Conflicts:
	src/Couchbase.Lite.Shared/Revisions/UnsavedRevision.cs
Complete issue #226

Ensure that db is open before set last sequence in Replication
Merge pull request #239 from couchbaselabs/issue-226

Complete issue #226
Merge remote-tracking branch 'upstream/master'