Initial creation of couchbase-lite-ios.podspec

This is the initial creation of `couchbase-lite-ios.podspec` which brings in `CouchbaseLite.framework`.  Another PR will be needed for `CouchbaseLiteListener.framework`.

This hopefully fixes https://github.com/couchbase/couchbase-lite-ios/issues/39#issuecomment-27607889.

This is what I modified for locally testing this podspec.
https://github.com/davidquon/Grocery-Sync-iOS/tree/cocoapod_test