Add server dev dep.

So that we can assert on making internal process connections.
Refactor to use latest constants.

Should allow removal of the obsolete COMMANDS constants, also add a test
for connecting to an internal server using createConnection(), identical
to the test in the server test specs but added for coverage.
0.1.20
Subcommands are accessed via nested objects.

So rather than client_getname it is now client.getname() which feels
cleaner, set timeout for ps/connect test spec, update mocha opts.
0.1.21