* Move CompositeSignaturesWithKeys into net.corda.core.crypto package.
(cherry picked from commit 8f29562)
* Rename and move CordaPluginRegistry to reflect its real purpose now.
Simplify serialization code a bit.
(cherry picked from commit e2ecd3a)
* Docs: docsite improvements
* Remove discussion of webserver from 'writing a cordapp' page.
* Fixup some flow docs.
* Add a couple more package descriptions.
(cherry picked from commit 2aedc43)
* Review comments
(cherry picked from commit ba1d007)
* Review comments - always apply default whitelist and no longer load it via ServiceLoader
(cherry picked from commit 7d4d7bb)
* Added wording about renaming services resource file
This improves the Java API and makes it more idiomatic. The methods
were not moved to be static methods of the relevant types in all cases
due to a bad interaction with a Kotlin auto-completion bug, and because
static methods on interfaces are new in Java 8 and Kotlin is not yet
emitting Java 8 bytecode.
Also, introduce a packages.md file so packages can be documented.
