Update copyright years to 2015

db.go

db_test.go

error.go

mongo/collection.go

mongo/connection.go

mongo/connection_test.go

mongo/database.go

mongo/database_test.go

mongo/id.go

mysql/connection.go

mysql/connection_test.go

net.go

ql/connection.go

ql/connection_test.go

ql/database_test.go

ql/template.go

settings.go

sqlite/connection.go

sqlite/connection_test.go

sqlite/database.go