Removed Bio-Formats from test-suite dependencies

Some Bio-Formats readers were superceding OME-TIFF for testing.
Eventually the test-suite will be completely converted for SCIFIO
classes. For now it is enough to remove Bio-Formats from the classpath,
and the one reference to Bio-Formats readers in the FormatReader test.
Added "exact" flag to TranslatorService

Translators (via the underlying PluginAttributeService) can now be
queried with an "exact" flag. If true, the translator must match both
Metadata classes exactly. If false, "isassignablefrom" is tested.
Updated uses as needed.
Added dummy EPSFormat Translator

Added an empty translator from ome.scifio.Metadata to EPSFormatMetadata.
This is to facilitate the EPS to OMEXML translator (which was looking
for an exact translator for EPSMetadata, which didn't exist).