Update to Java 7 (issue #23)
Merge pull request #25 from Wikidata/java-version-switch

Update to Java 7 (issue #23)
Added a first rough draft of the JSON parser for dumpfiles. Still work
in progress.

NOTE that the parser will introduce a new Maven dependency towards
"org.json"
Added further helper methods for the JSON parser.
Improved documentation.
=== Refactoring ===
Renamed JsonParser to JsonConverter since it represents better what the
class actually does.
Renamed variables to better represent, what they contain.

=== Assertions ===
Removed unneccesary assertions.
Added missing assertions.

=== Code general ===
Added further Methods so at least the top-level converting is complete.
Finer granularity is still work in progress.

=== Documentation ===
Added and improved documentation.
Changed the getDescriptions()-method to be consistent with the exception
handling of other methods.
Also added documentation.
Added a first rough draft of the JSON parser for dumpfiles. Still work
in progress.

NOTE that the parser will introduce a new Maven dependency towards
"org.json"
Added further helper methods for the JSON parser.
Improved documentation.
=== Refactoring ===
Renamed JsonParser to JsonConverter since it represents better what the
class actually does.
Renamed variables to better represent, what they contain.

=== Assertions ===
Removed unneccesary assertions.
Added missing assertions.

=== Code general ===
Added further Methods so at least the top-level converting is complete.
Finer granularity is still work in progress.

=== Documentation ===
Added and improved documentation.

Conflicts:
	wdtk-dumpfiles/src/main/java/org/wikidata/wdtk/dumpfiles/JsonConverter.java
=== Refactoring ===
Renamed JsonParser to JsonConverter since it represents better what the
class actually does.
Renamed variables to better represent, what they contain.

=== Assertions ===
Removed unneccesary assertions.
Added missing assertions.

=== Code general ===
Added further Methods so at least the top-level converting is complete.
Finer granularity is still work in progress.

=== Documentation ===
Added and improved documentation.

Conflicts:
	wdtk-dumpfiles/src/main/java/org/wikidata/wdtk/dumpfiles/JsonConverter.java
Changed data types and implementations to accommodate for the changed
data model.
Added outline for the statements conversion. Still work in progress.
Added some documentation and refined the outline.
Merge branch 'jsonToDataModel' of https://github.com/Wikidata/Wikidata-Toolkit into jsonToDataModel

Conflicts:
	wdtk-dumpfiles/src/main/java/org/wikidata/wdtk/dumpfiles/JsonConverter.java