Raster: disable setting the max extent constraint

Disable setting that constraint that seems to consume a lot of resources
when creating tables and is not needed for our use case.

See http://postgis.net/docs/using_raster_dataman.html

This is part of the improvements for #1492
Nil safe feature flag memoization and presence check
Improved feature flag check
CDB extension memoization
db_size_in_bytes memoization
db_size_in_bytes multiple load fixed in presenter instead of model
Avoid computing db_size_in_bytes twice
Increased default log level to debug so development servers display SQL queries
Merge pull request #1508 from CartoDB/fix-big-rasters-import

Raster: disable setting the max extent constraint
Update NEWS.md
Merge pull request #1511 from CartoDB/1505-Improve_dashboard_root_request

1505 improve dashboard root request
Assert UserNotifications created as expected
Merge pull request #1516 from CartoDB/fix-header-tests

Assert UserNotifications created as expected
updated cdb
merged with master