WIP: Http rework (#98)

- Move all HTTP tasks to a unified "MonitoredResource" model. This
   provides a uniform way of tracking object's lifetimes and disposing
   of them when complete.

 - Rewrite HTTP requests to use Netty instead of standard Java. This
   offers several advantages:
    - We have access to more HTTP verbs (mostly PATCH).
    - We can now do http -> https redirects.
    - We no longer need to spawn in a new thread for each HTTP request.
      While we do need to run some tasks off-thread in order to resolve
      IPs, it's generally a much shorter task, and so is less likely to
      inflate the thread pool.

 - Introduce several limits for the http API:
    - There's a limit on how many HTTP requests and websockets may exist
      at the same time. If the limit is reached, additional ones will be
      queued up until pending requests have finished.
    - HTTP requests may upload a maximum of 4Mib and download a maximum
      of 16Mib (configurable).

 - .getResponseCode now returns the status text, as well as the status
   code.

.gitignore

@@ -1,13 +1,17 @@
+# Build directories
+/classes
+/logs
 /build
 /out
+
+# Runtime directories
 /run
 /run-*
+/test-files
+
 *.ipr
 *.iws
 *.iml
 .idea
 .gradle
-/luaj-2.0.3/lib
-/luaj-2.0.3/*.jar
 *.DS_Store
-/test-files