The command used to invoke the LSP process was being escaped wrong.
Also added a new option to set a different java executable and fixed the
documentation.
Solargraph allows to set configuration options by creating a
.solargraph.yml file at the root of the project using it. Therfore this
file is a good canditate for finding ruby projects root paths.
Initial discussion:
https://github.com/w0rp/ale/issues/1874#issuecomment-418316168