Changes

Minor SCA-based fixes.
 (commit: 5df9c6a)

[Feature #38] Added tests for plural annotation property support.
 (commit: f8e160e)

[Task #42][Upd] Added JUnit 5 dependencies to the project (using Jupiter
vintage to run all the JUnit 4 tests). Updated some build plugins.
Migrated to Mockito 2.23.0.
 (commit: e5b0378)

[Feature #38, Task #42] Implemented support for plural annotation
properties.
 (commit: 2e9eb84)

Support setting subclass instances in polymorphic attributes (there was
an issue that caused PendingReferenceException because JOPA was checking
for instances of the attribute type and not the actual instance type).
 (commit: 3f98751)

[Fix] Fixed incorrect IRI of rdf:Property.
 (commit: 323a622)

Added definitions of a subset of the Dublin Core vocabulary.
 (commit: 02183b6)

Replaced uses of deprecated DC constants with the new ones.
 (commit: a213c7b)

[0.10.8] Bumped version and updated release notes.
 (commit: 6414933)