(TK-51) Move webrouting server info to config

Move the server info for each endpoint in the webrouting service
into the trapperkeeper configuration, rather than having the
user hardcode it when adding a handler with the webrouting
service.
(TK-51) Update docs and example with new config

Update docs and example for the webrouting service to reflect
the new configuration changes to the webrouting service.
(TK-50) Require user to specify default server

Require user to specify a default server when using a multiserver
configuration. Update docs and example to reflect this change.
(TK-50) Change default server configuration

Change the configuration of a default server to be a boolean
contained in the map for one server in a multiserver set-up.
Make the default server specification optional.
(TK-50) Remove atom

Remove atom being used in the get-default-server-from-config
function and replace it with a combination of first and filter.
(TK-50) Address PR feedback

Address the feedback on the PR for this ticket.
Merge pull request #52 from fpringvaldsen/TK-50-specify-default

(TK-50) Require user to specify default server
Merge pull request #54 from fpringvaldsen/TK-51-server-endpoint-in-config

(TK-51) Move webrouting server info to config
Support default-server option in webrouter

Modify the webrouting service so that it defaults to using the
default server set in the webserver service configuration rather
than a server with id :default.
Test default server requirement for webrouter

Add a test to the webrouting service that ensures that a default
server is required if any endpoints are not configured with
servers
Merge pull request #55 from fpringvaldsen/webrouting-fix

Use webserver's default server in the webrouter
bump project version to 0.7.0-SNAPSHOT
lein-release plugin: preparing 0.7.0 release
lein-release plugin: bumped version from 0.7.0 to 0.7.1-SNAPSHOT for next development cycle
update CHANGELOG.md for 0.7.0 release