add solidus_easypost file

[peterberkenbosch]

the extension is expected to have a solidus_easypost file to load the
engine and other libraries. This commit introduces that file that is
a simple wrapper around the existing spree_easypost file.

This fixes the problem with not loading migrations. ( fixes #30 )

[aitbw]

Thanks a lot for this PR, @peterberkenbosch ! 🙌

But I have a few questions:

• Wouldn't it be better if we renamed this file accordingly?

• If that's the case, shouldn't we rename the folder spree_easypost under lib/ too?

• It seems that this extension is missing a version.rb file under lib/spree_easypost/, what do you think about adding said file on this PR as well?

[peterberkenbosch]

yes, I agree @aitbw, this was the quick fix mode but the best is to rename it. I'll add the version file too.

[gildardoperez]

@peterberkenbosch OMG. Awesome! Thank you!

[peterberkenbosch]

@aitbw renamed all and introduced version file. Decided to go to a 2.0 version since we renamed it and this would be a breaking change.

[aitbw]

Fantastic work, @peterberkenbosch ❤️ 👏 thanks a lot for this patch! 🙇‍♀️

[aitbw]

What do you think on this, @kennyadsl @jacobherrington ?

[kennyadsl]

Thanks @peterberkenbosch, just left a suggestion 👍

[jacobherrington]

Thanks @peterberkenbosch!

[aitbw]

Let's wait to reach (and fix) a consensus on solidusio/solidus#3074 before merging this.

[aitbw]

Re-running specs now that solidusio/solidus#3078 and solidusio/solidus#3079 are merged.

[peterberkenbosch]

I will rebase this on master when #33 is merged. Thanks @aitbw

[aitbw]

Done with #33, @peterberkenbosch 👌

[aitbw]

Re-running specs due to a Travis failure.