Support saving / loading of programs from server

[ocadotechnology]

Support saving / loading of programs from server

[andersschuller]

We could use the built-in cloud storage support?

https://code.google.com/p/blockly/wiki/CloudStorageWithAppEngine

[andersschuller]

From their demo and their source, it looks like the built-in cloud storage support is just a special request handler that saves the serialised XML of the workspace under a unique id. Since we were already working on serialising the instructions in our own way, and I imagine we want to do things like let users see their list of saved programs (which they may have given useful names), I think we should just do this ourselves. In that case it will work when not running in App Engine also,

[robertbrignull]

Saving and loading has been implemented in commit f52563c. I decided to use blockly's default serialization. The server code is a bit ugly and hacky with the handling of PUT data so I think if we're going to do any more REST style stuff we should pick and use a proper framework, that's a discussion for a different issue however.