Modified Gruntfile.js to look for .thrift files in concrete-thrift

The Gruntfile.js build file now looks for the .thrift definition files
for Concrete in a copy of the concrete-thrift repo at
${HOME}/concrete-thrift, instead of in a copy of the concrete repo at
${HOME}/concrete.
Regenerated Concrete classes using newest Thrift schema
Uses updated schema where UUIDs now represented by classes instead of strings