fix raw tag parsing to work for multi-line HTML

[SampsonCrowley]

fixes raw tag parsing mentioned in #95

[marcandre]

Interesting PR.

I only looked at it quickly and I'm not the final authority on this gem, but a few things come to mind:

1. this mixes independent changes (config vs raw tag). Ideally these would be separate PRs. Also never change version numbers in a PR, that's the job of the maintainers.

2. For the raw tag, the issue I see is that inky-rb is meant to be the Ruby port of inky, so it should probably support raw tags iff inky does.

3. For the config part, I believe that ignoring bad values passed (e.g. test "will not set an invalid components override") is not the right way to go. Raise a TypeError instead.

[SampsonCrowley]

@marcandre

1. good point, I will split it into separate PRs

2. this repo already supports raw tags, but the current implementation in this repo only checks a single line at a time. this is an HTML based library, that's not how users expect HTML parsing to work

3. another good point, will fix

[marcandre]

2. Oh, right, my bad.