Removes unused "preload_on_init" option.
Merge #589 r=@kevinmehall: Removes unused "preload_on_init" option.

This is broken on master, since process is instantiated **after** libs are preloaded, anyway.
removing hardcoded dns
check for no connection

making things easier to read

forcing uint8_t
Merge #593 r=@jiahuang: remove hardcoded dns

goes with https://github.com/tessel/firmware/pull/101

Changes DNS from 8.8.8.8 to whatever Tessel picks up. 

On PC colony it still defaults to 8.8.8.8.
Added neopixel builtin
Merge #596 r=@kevinmehall: Added neopixel builtin
prepends process version with a v for compat with node
Merge #598 r=@johnnyman727: prepends process version with a v for compat with node
Updates Travis
Removes explicit "bit32" library load, making it global.
Merge #600 r=@tcr: Updates Travis
Adds compilation ability for LuaJIT with ENABLE_LUAJIT=1
Merge #601 r=@kevinmehall: Add compilation flag for building against LuaJIT or Lua VMs.

Replaces #528 with a direct merge into master.

`make` will continue to target the Lua VM by default. This adds a `make` option to generate a runtime build targeting LuaJIT. This isn't intended to be long-term (the Lua VM will just be removed eventually) but to provide greater opportunities for testing coverage before enabling it by default.

```
make ENABLE_LUAJIT=1
```
match undocumented http.Agent inheritance, fixes #603
Ensures GYP always invokes LuaJIT makefile.
Performs stringification of keys in assignment in JIT.
Adds testcase for NOT on negative numbers. Fixes #605.
Restores FFI support on Linux.
Makes luajit-build work on Darwin/GCC. Fixes Buffer incompat.