pipeline_lua: embed base Lua code during the build process

This change lets us write Lua code that gets linked in to the binary. The goal
is to set up the sandbox from Lua, rather than making lots of calls to the C
API.
luajit: silence commands when VERBOSE is not set
pipeline_lua: create a sandbox

See http://lua-users.org/wiki/SandBoxes. The goal is to hide builtin functions
like os.exit from uploaded code.

There are a few holes remaining:

1. FFI
2. Raw _context pointer
3. register_table passes raw pointers
4. Need time/memory limits on scripts
5. Bytecode may be unsafe
6. field_names may need to be copied
pipeline_lua: support multiple builtin Lua files
pipeline_lua: expose simple actions to sandbox

The non-scalar set-fields of MACs and IPv6 addresses are going to be more
complicated.
pipeline_lua: add a log function
action: add scalar version of MAC rewrites for Lua

It's easier to pass plain integers through the Lua FFI.
pipeline_lua: use scalar MAC rewrite actions
pipeline_lua: safely expose packet fields to uploaded code
pipeline_lua: add licenses to embedded Lua code
Merge into master from pull request #221:
pipeline_lua: embed base Lua code during the build process and create sandbox (https://github.com/floodlight/ivs/pull/221)