Module version checks for compatibility with API changes to ES 1.0

When ES 1.0 comes out the API will be a bit different.  This is planning for the change.  This will allow the current version of curator to continue to work with 0.90.x (and potentially older versions).  

A few minor changes will also prevent the 1.0 release of curator (version bump anticipated to match python module versioning *and* ES version 1.0) module from working with older versions.