Standardized <p> tag locations in javadoc.
Standardizing application of annotations.
Assigning TODOs to self.
Renaming all expected exceptions "expected".
Removing redundant import.
Add check for double store assignment.
Standardizing line breaks (best-effort).
Document use of | instead of ||.
Add more details to javadoc of native driver.
Store class is "conditionally" thread-safe.
Refactor filename regex for readability.
Improve regex for valid filenames.

- Include max length, so don't need to check again.
- Exclude DEL (0x7F) control character.
More comprehensive tests for filename checks.

- Add check for DEL (0x7F) character.
- Add sanity check for filename exactly at max length.
Simplify filename regex with lookaround.
Move line-break.
Modify storage I/O reasons.

* Generalize read/write error reasons (non-file specific).
* Add "key too large" reason.
* Add "driver-specific" reason.
Change filename regex to pure blacklist.

- The whitelisting construct was redundant.
Remove dependence on AESKeyVersion.

* Switched to mock key version for testing.
Make comment clearer.
Change method param to general interface.