emacs: Append merlin-ac-source to ac-sources instead of replacing it.
emacs: Append merlin-ac-source to ac-sources instead of replacing it.

Closes #19.

ocaml/merlin,dra27/merlin,chambart/merlin,chriskonstad/merlin,ocaml/merlin,fxfactorial/merlin,dra27/merlin,haselwarter/merlin,neojski/merlin,the-lambda-church/merlin,haselwarter/merlin,the-lambda-church/merlin,haselwarter/merlin,neojski/merlin,chambart/merlin,chambart/merlin,dra27/merlin,rgrinberg/merlin,rgrinberg/merlin,neojski/merlin,dra27/merlin,ocaml/merlin,fxfactorial/merlin,ocaml/merlin,rgrinberg/merlin,rgrinberg/merlin,chambart/merlin,chriskonstad/merlin,haselwarter/merlin,the-lambda-church/merlin,fxfactorial/merlin,neojski/merlin,fxfactorial/merlin