Bump version to 0.4.9.
Add parameter docs.
Use a block to cache parsed source files.
Reuse directory name.
Use subject rather than ivar.
Tweak comment.
Use struct to pair certificate with its private key.
Fix documented return type.
Extract save method.
Add trusted? tests.
Ignore duplicate certificates when building store.

Fixes #37.
Loosen gem dependencies.
Brevity.
Add parameter docs.
Freeze constants.
Make header attributes easier to scan.
Use a real variable name.
Improve docs.
Add docs.
Multi-line blocks use do/end.