chore(emacs/Cask): add ert-runner, ecukes
doc(emacs/README.md): add contribution section
refactor(emacs): move tests in *.el files to 'test' directory
test(emacs/features): add ecukes template
chore(emacs/lean-server): make trace-mode and debug-mode non-local vars
fix(emacs/lean-server): handle modified buffer only when process start
fix(emacs/lean-company): repaint background in the candidate only when required
fix(emacs/lean-company): pass dummy continuation for WAIT