added sbumodule for ProofExplorer
indentation format for json schema and some description updates
Merge commit 'e1e1bd88dc03a776da4c5f7085b567742902e9f2'

* commit 'e1e1bd88dc03a776da4c5f7085b567742902e9f2':
  Update the README file to point at travis, along with some more documentation.
  Add support for testing PVS against SBCL automatically using Travis CI.
added pvsio-web submodule and readme in javascript folder to describe how to setup and run the submodules.
reverting pvs-gui.json
updated javascript/README.md to contain screenshots of tools.
Merge pull request #38 from thehogfather/master

Javascript tools submodules
Fix the check-model step under SBCL.

Fix various problem with the check-model step when PVS is compiled against
SBCL:
 - Wrap the mu___append_cont so that 32bit numbers are converted to pointers.
Otherwise SBCL throws type errors.  To avoid compatibility issues, the alien
interface isn't changed.
 - Fix comparisons involving c pointers.
 - Properly check for null pointers, using an implementation proper way.  SBCL
requires a proper null check instead of just comparing the pointer to zero.