Add column disease_occurrence.distance_from_extent
Move constants in NativeSQLImpl into a NativeSQLConstants class. Introduce boolean parameter into routine for admin unit global/tropical.
Disease extent generation now populates a disease_extent table with the aggregated disease extent that will be used in distance calculations.
Fix checkstyle violations
Calculate the distance from disease extent for relevant occurrences. If the occurrence location is within the disease extent, the distance is a negative value and is fixed for each relevant disease extent class (see the new column disease_extent_class.distance_if_within_extent).
Merge branch 'master' into 169-distance-from-disease-extent

Conflicts:
	src/Common/src/uk/ac/ox/zoo/seeg/abraid/mp/common/dao/NativeSQLImpl.java
	src/ModelOutputHandler/test/uk/ac/ox/zoo/seeg/abraid/mp/modeloutputhandler/web/MainControllerIntegrationTest.java
Merge pull request #126 from SEEG-Oxford/169-distance-from-disease-extent

Calculate the distance from disease extent for each relevant occurrence