Moved AttributeService to Services package

The discovery package is scheduled for deletion once all annotations are
converted to scijava plugins.

The services package is appropriate for scifio services extending
scijava-common functionality.
Converted Services to scijava plugins

All of the legacy "services" have been converted to scijava-common
plugins, to unify the separate discovery mechanisms and eliminate the
scifio ServiceFactory.

Eliminated ome.scifio.discovery package, in favor of
ome.scifio.services.
Removing DatasetMetadata interface

Separately tracking Metadata and DatasetMetadata is cumbersome.
Especially given that all readers need both, so a given Metadata will
ALWAYS be translated to DatasetMetadata.

Instead, the Metadata and DatasetMetadata interfaces have been merged.
This means that any Metadata instance will be able to provide the
corresponding standard ImageMetadata information.

This also greatly simplifies translation, as there is no need for
translators to DatasetMetadata any more.
Added scijava common to ome-io build.properties

Updated the ome-io component build.properties to include scijava-common.
Added log4j jars to test-suite classpath

Updated test-suite build.properties to include log4j jars, as it was
failing to compile.
Added RAOS fixme to AbstractWriter

Reminder for the future of RandomAccessOutputStream
Legacy writers get existing formats

The converted Legacy writers no longer construct their own Formats,
instead pulling from the current context.
SCIFIOFormatWriter leverages MetadataRetrieve

The SCIFIOFormatWriter now takes advantage of OMETranslators to extract
data from its attached MetadataRetrieve, and populate its corresponging
SCIFIO Metadata.

Consolidated repeated code to this abstract layer.
InitializeService sets dataset name

Sets the destination on the output Metadata in the initializeWriter
method.
Removed translator constants

These DEST_VALUE keys are not necessary any more, since a general
Metadata name constant can be used.
Made OME translation API more robust

Added To and From OME translator interfaces and added skeletons for the
"from OME" translators.

Translation must be available in both directions for OMEMetadata to be a
functional intermediary storage (as it was in bio-formats).
Fleshed out ImageMetadata population method

The OMEXMLMetadataService method populating ImageMetadata using a
MetadataRetrieve has been fleshed out.
Added Dimension population methods

SCIFIOMetadataTools now has a set of standard populateDimensions method
signatures for populating the axes of ImageMetadata. The goal is to
standardize this and reduce code repetition.
fix: added class-based translator lookup
fix: added ics setter methods
fix: OMETranslator work
fix: added Context constructor to OMEMetadat
fix: guaranteed axis lengths == 1 in scifiometadatatools
fix: added priorities to ome translators
fix: moved isVersionTwo from ICSFormat to Parser