Repair data type conversion (Oracle to Postgres) errors

The root cause of the errors reported in FT-809 and FT-811 could be traced back to data type errors for some of the database fields involved in the calculation of e.g. zscore. A number of those fields have bigint type (in Postgres, was NUMBER type in Oracle). This (bigint type) introduces rounding errors and in some cases (depending on the values uploaded) even resulted in all zscore values to be equal to "0.0".