A new web-site for Abella

The Abella interactive theorem prover now has a new web-site: http://abella-prover.org.

Relatedly, the canonical GitHub repository for Abella has been changed to: http://github.com/abella-prover/abella. Kaustuv Chaudhuri (Parsifal) and Yuting Wang (Univ. Minnesota) join Andrew Gacek (Rockwell Collins) as maintainers of Abella.

A cumulative new release of Abella is planned during the remaining months of 2012. A beta version is expected to be released in November.