Fix parsing of UNION

Previously SELECT 123 UNION DISTINCT SELECT 123 UNION ALL SELECT 123 was
parsed as SELECT 123 UNION DISTINCT SELECT 123 UNION DISTINCT SELECT 123
Add test query for previously broken UNION query
Fix parsing of INTERSECT
Increase test timeout to 60secs to resolve random failures
Move accumulator state size to a static constant
Remove unnecessary parameter documentation
Fix trailing whitespace
Cleanup TABLESAMPLE documentation
Update documentation for SELECT
Cleanup source for color function documentation
Update SPI documentation
Exclude REST documentation

This needs more editing before it can be published.
Add configuration for s3 max connections

Change default s3 msx connections to 500 and make it configurable
Allow Verifier to specify the jdbc driver for control and test
Expose queryId in PrestoResultSet
Improve support for numeric fields in json extract

Allow numeric fields without quoting in path expressions
Numeric fields match both array elements and object fields
Add 0.75 release notes
Fix style error
Document MAX_BY and update 0.75 release notes
Remove unnecessary .gitignore