Fix Rebar Support (lordnull#27)

With this, projects using rebar should be able to use rec2json again (e.g., resolves lordnull#26 ).

Merge pull request lordnull#25 from lordnull/mw-use-erlang.mk

use erlang.mk

Bumped version number.

Adding a new type conversion counts as adding a feature as far as this
project is concerned.

Fixed handling skipped fields.

Bug fix for field types list(#r{}).

version 3.0.1

Merge pull request lordnull#12 from lordnull/update-to-18

Update to 18

Version 2.1

Bumped version.

add 2.0.3 tag