implement .jpmignore
add unit test for .jpmignore
fix typos
tweak lib/ignore.js

- only process data read from .jpmignore
- do not join and split default rules
- change separators used in split to improve readability
add unit tests for jpmignore with different line-endings
Merge pull request #228 from uFFFD/jpmignore

Issue #168: implement .jpmignore r=erikvold