Store entry_places on the net as constants
/nets/<net_key>/places/<place_name> -> <place_idx>

In order to start the net, the response from submitting a net now
includes a list of entry_links.
Improve error reporting
fix tests: should have been done with inclusion of variables and constants
Split out views from api again

Using url_for from flask directly instead of from restful.
Return only what is needed from the backend

Returning a net object is dangerous because the view could then mutate
the state of the net which violates mvc.
Only store place-to-index lookup for entry_places
Optimize lookup of entry_places
Merge pull request #11 from davidlmorton/master

Fix API: place_name should be place_idx

Merging even though travis-ci did not correctly run tests on commit 125194f (instead it ran on e6add11).