[Fix #593] Restore compatibility with Emacs 24.3

Turns out the `thing-at-point' NO-PROPERTIES argument was introduced in Emacs 24.4.
[Fix #593] Fix error with no symbol at point
Merge pull request #595 from johnwalker/fix-593

[Fix #593] Fix error with no symbol at point
Fix showing documentation with company-doc-buffer.

Update company-doc-buffer to use new doc fn.

Add option to cider-doc-lookup to select the newly-created window.