add ac-dcd-add-imports function

This function sends import flags of the current DUB project to
dcd-server.
cleanup readme
fix typos
fix goto definition with respect to UTF-8 encoding
Merge pull request #157 from snosov1/fix-goto-definition

fix goto definition with respect to UTF-8 encoding
Merge pull request #156 from snosov1/fork-dub-imports

Add ac-dcd-add-imports function