Move adapter properties to base class

Move some properties of the adapters to the base class where they can be
shared.

Change-Id: Ie38d0a7d05e7be92c4e0592b7f3cc3c232723df6
Switch from ContextAdapter to ContextFormatter

Remove the ContextAdapter and update getLogger to return
KeywordArgumentAdapter instances instead.

Update the JSONFormatter to do some context magic like the
ContextFormatter does so the extra properties from the context and the
KeywordArgumentAdapter are included in the output JSON package.

Update the ContextFormatter to include some nova-specific behavior that
was in ContextAdapter. We will replace that with changes to the way the
default log format strings are constructed in a later patch.

bp/remove-context-adapter

Change-Id: I5a96d55355bf4ef68f2ee71160a3e0200c371e87
Merge "Move adapter properties to base class"
Merge "Switch from ContextAdapter to ContextFormatter"