(TK-3) Rename WebserverServiceContext schema

Rename WebserverServiceContext schema to ServerContext, as this
will now represent the context for a single server within the list
of servers.
(TK-3) Wrap ServerContext in map

Wrap ServerContext (which was previously WebserverContext) in a
map, which is now stored in the service context under the
:jetty9-server key. This map will hold the contexts for multiple
servers.
(TK-3) Change :jetty9-server key

Change :jetty9-server key in the context to :jetty9-servers to
reflect the fact that the item stored at that key can now hold
multiple servers.
(TK-3) Add server-specific service functions

Add server-specific versions of all the service functions. These
take in a server-id as an additional parameter, and perform
the corresponding operation on that server and update that
specific server's context. The old versions of the functions
now call the new versions, with :default passed in as the
server-id.
(TK-3) Add support to init and start

Add multi-server support to start and init lifecycle functions.
They now have code to add/interact with multiple servers
in a server map if so specified by the user in the configuration
file.
(TK-3) Add support to stop function

Add multi-server support to the stop function. It will now go
through the full list of servers and shut each one down.
(TK-3) Rename WebserverServiceConfig schemas

Rename the WebserverServiceConfig schema to WebserverConfig
and the WebserverServiceRawConfig to WebserverRawConfig, as these
now represent configurations for single servers rather than the
whole service.
(TK-3) Add multiserver service test

Add multiserver service test. This validates a ring handler
on a single server set up using the new syntax, and
validates two ring handlers set up on two different servers
at the same time.
(TK-3) Add multiserver shutdown test

Add multiserver shutdown test. This test throws an error in the
startup function for a service that depends on the Jetty service
and has a multi-server setup. It ensures that all the servers
are successfully shut down after the error is thrown.
(TK-3) Change multi-server config syntax

Change the multi-server configuration syntax. Configuring
multiple servers is now done under the :webserver key instead of
the :webservers key. Under this key, one can configure multiple
servers with the new syntax, a single server with the new syntax,
or a single server with the old syntax.
(TK-3) Change names in for

Change names in for bindings to be more descriptive of what
the variables represent. Also, remove superfluous line from
init function.
(TK-3) Move things to let statements

Move various functions into let statements to increase
readability of code.
(TK-3) Add default behavior test

Add a test of the default behavior when given an old-format
configuration file. Checks to make sure that :default is in
the context list, that it is a valid webserver context, and that
the :default server has been started.
(TK-3) Move default-context into let

Move the acquisition of the default server's context into a let
statement to increase readability
(TK-3) Add default for endpoint functions

Change current versions of get-registered-endpoints and
log-registered-endpoints to have a -from suffix, and add
new get-registered-endpoints and log-registered-endpoints
functions that do not take the server-id, and simply call
the -from versions passing in :default as the server-id.
(TK-3) Move lifecycle functionality to core

Add functionality for init and start lifecycle functions into
core so that the lifecycle functions have as little in them
as possible.
(TK-3) Enforce more specific schemas

Enforce more specific schemas on the configuration. All set-ups
must now have a server with id :default, and the
configuration is now validated as well. Change to cond statements
instead of if statements. Refactor init! and start! functions
to make them more readable.
(TK-3) Push service handlers into core

Push the implementation of the service handler functions into
core. This avoids cluttering up the service handlers themselves
and allows validating that the server-id is a keyword.
(TK-3) Add tests for default add-ring-handler

Add tests that test add-ring-handler (as opposed to
add-ring-handler-to).
(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.(TK-3) Add tests for -to functions

Add tests for -to versions of service handler functions.