Update travis build matrix
Update travis build matrix

Use Go 1.6.0
Add PostgreSQL 9.5
Remove PostgreSQL 9.0 as it is no longer a supported version
  http://www.postgresql.org/support/versioning/

silviucm/pgx,silviucm/pgx,jackc/pgx,plopik/pgx,jackc/pgx,silviucm/pgx,plopik/pgx,jackc/pgx,plopik/pgx,jackc/pgx