Reindent for flatness
Factored out error construction
Refactor for readability
Make methods non-static
Added an OS_X SecurityCommand class and a `.store` attribute on the keyring to support keys stored in the 'internet' store. Fixes #10.
Bumped to 2.1 in preparation for next release.

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extra : source : c7881246b8d233fbfd47fa0d10d0b966c905375a
Added tag 2.1b1 for changeset 01a217c7cedc