Allow a path to be given to ElixirScript compiler #420

To support .exs files, ElixirScript should support compiling paths given to it.

Allowed paths should be:

my/path/to/files
my/path/to/files/file.ex
my/path/to/files/file.exs
my/path/to/files/**/*.exs

This is a bit more complicated since the beam data will be in memory. Luckily, Elixir's ParallelCompiler can be used to get the in memory beam data. From there ElixirScript can get the debug info out of the data.