Improve the user experience for initial startup (resolves #697).

Sending this out early to get feedback. Things seem to work.

* Takes the server process into account when computing the 'mode-line'. If a given source file 'belongs' to a server process, but there is no connection present, the mode-line will read 'Starting...'. This motivated some refactoring of the 'owning-connection-for-source-file' logic, moving much code to ensime-config.

* Replenishes connection attempts if the server buffer shows any action.

* Pops the server buffer in a secondary window when you run M-x ensime (without stealing focus). The idea being to make it obvious what is taking so damn long.


It would be nice to delete that window once we're in the connected state.