OME ontologies: schemas and samples reorganization

[sbesson]

Implements the first part of the proposal described in #89

• specification/samples are migrated under specification/src/main/resources/samples and should be packaged as part of the specification JAR
• the XSD schemas underspecification/src/main/resources/relased-schemas are renamed as specification/src/main/resources/relased-schemas
• the corresponding references across the repository (publication script, Cmake files) are adjusted to consume the new paths

With these changes, it should be possible to create specification/src/main/resources/ontologies and add additional samples to specification/src/main/resources/samples.

/cc @joshmoore @norikoba

[sbesson]

After second thought, closing this PR.

Although I still believe we want to fix the name eventually, renaming the released-schemas/ directory might just put unnecessary last minute changes while we try to review and freeze the various components for Bio-Formats 6. More importantly, it does not preclude the addition of the 2016-06 ontology as another top-level directory.

Similarly, packaging the samples as part of the JAR (3977bc7) is hopefully valuable but it should be good to drive this feature using a concrete use case.