* [FIX] do not auto load server_environment_ir_config_parameter
When a module has a static directory, it is preloaded by the
Odoo http server. This breaks installations which do not have
nor need server_environment_file addon.
* [IMP] update server_environment caveat
This is much more robust that raising an error, and let modules
load ir.config_parameter from xml data files, while still enforcing
values from the config files.