Removed incorrectly added vimsession subtree

Somehow this commit ended up in the repository root, when it should be
under .vim/bundle/session. This commit removes it.
Squashed '.vim/bundle/session/' content from commit ca2e72f

git-subtree-dir: .vim/bundle/session
git-subtree-split: ca2e72f5ace2eeff48fc1619b0fd5eedf4ba00be
Merge commit '38b2a91d2e9dc0524387d17fcf5293d02f6e0275' as '.vim/bundle/session'