A few small things

Just a few small changes/fixes:

* Moved the tests from Omnisharp.Tests to OmniSharp.Tests and made some similar case changes to a couple of other names
* Fixed a bug introduced in d8dfb228ad which broke completion on project-less files for me
* In the vim script, made the base of the server url set via a vim variable instead of a python variable.  This way it can be changed easily from within vim.
* Changed the cursor column position sent to be the cursor position for a completion to be the position when OmniSharp is called the first time.  Sending the cursor position from the second time it is called causes incorrect completions.