elisp: adding .cask files to gitignore

cask is a dependency/package management tool for Emacs lisp packages. Adding
.cask to gitignore template to avoid tracking of installed packages not
a part of repository
Update C.gitignore

Added .la and .lo library extensions
Merge pull request #1125 from eugpermar/master

Update C.gitignore: Added .la and .lo library extensions from GNU libtool
Merge pull request #1096 from theanalyst/elisp/cask

elisp: adding .cask files to gitignore