Updated where one could download the pre-build images of Ensime.
Fixed example to use the latest pre-build Ensime version numbers:
ensime_2.9.2-0.9.8.9 and ensime_2.10.0-0.9.8.9
Communications with the server is now both asynchronous and synchronous.
Generally, asynchronous will still be used for standard communication
while synchronous is used for unit tests. Maybe, in time, some of the
commands will be synchronous - maybe configurable via Options.
Added unit tests.
Tests require runVimTests-1.22.zip and vimtap-0.4.0.zip.