Fixed calculation of calendar date from fiscal-year values.

The implementation was actually missing. Added some tests to ensure that
this won't happen again..

Signed-off-by: Sebastian Hoß <mail@shoss.de>
Prepare for next release.

Since we are using semantic versioning, user can actually use version
ranges to specify their dependency on fiscal-year, without breaking
their builds.

Signed-off-by: Sebastian Hoß <mail@shoss.de>
[maven-release-plugin] prepare release fiscal-year-1.0.1