dup 2.0 code examples

First comment:

*DB 16*

Swift

• Support Database Encryption
• Implement a new index API
• Move FTS.rank expression to Function.rank()
• Make Replicator's User-Agent header that includes information about library version and platform.

C#

• Collation API now supported on Android
• Redid Index API (indexes are now identified by name). See the new `Index` class documentation.
• Encryption is now supported. Encryption keys can be added onto the `DatabaseConfiguration` class. This will encrypt database files and attachments.
• Added in a `rank()` function for `IExpression` to order by FTS ranking result
• Made a consistent User-Agent string that gets info on which platform is running
• Changed the default Collation locale to be the one currently running on device

*DB 15*

iOS/Swift

• Support Collation Expression.
• Support FTS Ranking Value Expression.
• Support database copy to allow to install a canned database.
• Allow to set logging level.

Java

• Thread-safe with Database operation. (Other operations will be a thread-safe with next DB release)

C#

• Collation API now supported on Linux platforms (Android coming soon)
• Statically compile, so iOS 9 will work now
• Add a database copy API (note: current behavior will replace an existing database, but this may change) to make copies of a database (useful for seeding and/or backup).

see other comments: https://github.com/couchbaselabs/couchbase-mobile-portal/issues/802