Add LibJIT bindings by Peter Nelson
Add documentation to LibJIT
Remove unnecessary boxes
Include JIT as extern crate
Revert "Get rid of unnecessary boxes"

This reverts commit f7bddfb513e0f65314bb38095e13f37136a91fd3.
Update Makefile
Implement basis for JIT compilation
Update travis build script to work with libjit
Add textinfo install for libjit build
Move git clone into before_install
Seperate JIT function creation and JIT value creation into seperate functions and implement operators
Implement Neg for ValueData
Implement some unary ops
Update to use String in place of StrBuf to match Rust master
Remove unused variables in JIT Compiler
Make `undefined` and `null` work with lastest release
Add default return
Restructure JIT Compiler to return the value instead of setting a pointer to it
Implement JIT for return expression
Implement throw in JIT