Add logic to set release/version number of the formats documentation

Since minor schema releases are still identified by date, Sphinx version and
release numbers are identical for now.
Merge pull request #13 from sbesson/formats_release

Add logic to set release/version number of the formats documentation
Merge pull request #14 from qidane/formats1

Move the images to under the formats directory and adjust build
Edits to OME-TIFF section
Edits to XML, schema & specifications sections
Add recommended shebang line to conf.py
Heading consistency & improving using OME-XML
renaming long file & fixing broken link