organize t/share directory better

I also discovered that some tests are sharing t/share directories when
they shouldn't, like t/store.t
remove spurious test collateral

Multiple documents per file is not currently a feature of Statocles.
cleanup store tests to use files

Stop making the blog documents and theme files serve double-duty for the
store tests, making it harder to isolate the two.
make sure store is always using utf-8

For now, UTF-8 is the best option for character encodings. In the
future, we might be able to offer reading from whatever character
encoding the user is using.

Fixes #145