Convert all bigint database columns to integer. Refactor the Java code accordingly. The columns were originally bigint due to misinterpreting HealthMap's MySQL data type "int(11)" (this does NOT mean an integer with up to 11 significant figures, the 11 refers to how the integer is displayed).
Merge pull request #105 from SEEG-Oxford/176-bigint-to-int

Convert all bigint database columns to integer.