API Change: Added set/delete cookie methods to CBLReplication

This is used for setting custom session/auth cookies. Most useful if
the cookie was returned from a different subdomain and should also be
used with the replication server.
Oops, fixed a compile error from the previous commit
Overhauled project/build versioning.

* Existing CURRENT_PROJECT_VERSION setting is used as the "serial
  number" of the build. This will be set only by the automated build
  environment (not checked into the project.)
* A custom build setting CBL_VERSION_STRING defines the "marketing
  version number", e.g. "1.0" or "1.1 beta 3". This is checked into
  the project but will be overridden by the automated builds.
* An optional custom build setting CBL_SOURCE_REVISION contains the Git
  revision ID of the source code. This is only set by automated builds.
* The result of CBLVersionString() is generated from the project version
  and version string.
* The HTTP User-Agent header sent by the replicator is generated from
  the version string and OS/platform name (Mac OS X or iOS.)
* All three versions are logged at startup time using Log().
Verify that revisions with identical content have the same rev id.

https://github.com/couchbase/couchbase-lite-java-core/issues/164
Added test for behaviour of attachments not being push replicated for new document revision if only JSON body is updated.
Some build fixes

* Fixed a typo that broke the iOS build
* Add CBLAuthenticator.h to framework headers directory
Fixed regression where unchanged attachments get re-sent on every push

Fixes #326
Merge branch 'feature/issue_326'
Merge pull request #324 from couchbase/cblite_java_issue_164

Verify that revisions with identical content have the same rev id.
Fixed: WebSocket _changes feed wouldn't connect over SSL

It would try to connect over plain HTTP and fail, because I put the
-startTLS: call too early.
Also, I enabled cert hostname verification, which is an important safe-
guard against MITM attacks.

Fixes #332
Fixes #333
Fixed bundle version strings.
Merge branch 'master' of https://github.com/couchbase/couchbase-lite-ios