Ensure that when running the lfe binary, all libs are accessible

[oubiwann]

Part of feature #16

[oubiwann]

Looks good:

$ ERL_LIBS=_build/default/rel/olp/lib/ _build/default/rel/olp/bin/lfe

Erlang/OTP 18 [erts-7.3] [source] [64-bit] [smp:4:4] [async-threads:10] [kernel-poll:false]

   ..-~.~_~---..
  (      \\     )    |   A Lisp-2+ on the Erlang VM
  |`-.._/_\\_.-':    |   Type (help) for usage info.
  |         g |_ \   |
  |        n    | |  |   Docs: http://docs.lfe.io/
  |       a    / /   |   Source: http://github.com/rvirding/lfe
   \     l    |_/    |
    \   r     /      |   LFE v1.2.0 (abort with ^G)
     `-E___.-'

> (code:root_dir)
"/usr/lib/erlang"
> (code:get_path)
("."
 "/usr/lib/erlang/lib/kernel-4.2/ebin"
 "/usr/lib/erlang/lib/stdlib-2.8/ebin"
 "_build/default/rel/olp/lib//sasl-2.7/ebin"
 "_build/default/rel/olp/lib//lutil-0.10.0-rc4/ebin"
 "_build/default/rel/olp/lib//ltest-0.10.0-rc4/ebin"
 "_build/default/rel/olp/lib//lfe-1.2.0/ebin"
 "_build/default/rel/olp/lib//compiler-6.0.3/ebin"
 "_build/default/rel/olp/lib//color-1.0.0/ebin"
 "./_build/default/lib/color/ebin"
 "./_build/default/lib/lfe/ebin"
 "./_build/default/lib/ltest/ebin"
 "./_build/default/lib/olp/ebin"
 "./_build/default/lib/lutil/ebin"
 "/usr/lib/erlang/lib/xmerl-1.3.10/ebin"
 "/usr/lib/erlang/lib/wx-1.6.1/ebin"
 "/usr/lib/erlang/lib/webtool-0.9.1/ebin"
 "/usr/lib/erlang/lib/typer-0.9.10/ebin"
 "/usr/lib/erlang/lib/tools-2.8.3/ebin"
 "/usr/lib/erlang/lib/test_server-3.10/ebin"
 "/usr/lib/erlang/lib/syntax_tools-1.7/ebin"
 "/usr/lib/erlang/lib/ssl-7.3/ebin"
 "/usr/lib/erlang/lib/ssh-4.2.2/ebin"
 "/usr/lib/erlang/lib/snmp-5.2.2/ebin"
 "/usr/lib/erlang/lib/sasl-2.7/ebin"
 "/usr/lib/erlang/lib/runtime_tools-1.9.3/ebin"
 "/usr/lib/erlang/lib/reltool-0.7/ebin"
 "/usr/lib/erlang/lib/public_key-1.1.1/ebin"
 "/usr/lib/erlang/lib/percept-0.8.11/ebin"
 "/usr/lib/erlang/lib/parsetools-2.1.1/ebin" ...)
> (lutil:uuid4)
#"5327429a-9477-43f6-031b-644d213fc6ca"
>