Clean up some references to Caddy

Simple rename of Caddy/CoreDNS and some smallish cleanups.

See #1

.gitignore

@@ -1,16 +1,2 @@
-.DS_Store
-Thumbs.db
-_gitignore/
-Vagrantfile
-.vagrant/
-
-dist/builds/
-dist/release/
-
-error.log
-access.log
-
-/*.conf
-Caddyfile
-
-og_static/
+query.log
+Corefile

CONTRIBUTING.md

@@ -1,6 +1,6 @@
 ## Contributing to CoreDNS
 
-Welcome! Our community focuses on helping others and making Caddy the best it
+Welcome! Our community focuses on helping others and making CoreDNS the best it
 can be. We gladly accept contributions and encourage you to get involved!
 
 ### Bug reports
@@ -56,5 +56,4 @@ If it's not a big deal, a pull request will probably be faster.
 
 ## Thank you
 
-Thanks for your help! CoreDNS would not be what it is today without your
-contributions.
+Thanks for your help! CoreDNS would not be what it is today without your contributions.

middleware.md

@@ -17,7 +17,7 @@ From the Caddy docs:
 In the DNS status codes are called rcodes and it's slightly harder to return the correct
 answer in case of failure.
 
-So CoreDNS treats
+So CoreDNS treats:
 
 * SERVFAIL (dns.RcodeServerFailure)
 * REFUSED (dns.RecodeRefused)