Until now, running `db:dev_seed` created development data for the
default tenant but it was impossible to create this data for other
tenants.
Now the tenant can be provided as a parameter.
Note that, in order to be able to execute this task twice while running
the tests, we need to use `load` instead of `require_relative`, since
`require_relative` doesn't load the file again if it's already loaded.
Also note that having two optional parameters in a rake task results in
a cumbersome syntax to execute it. To avoid this, we're simply removing
the `print_log` parameter, which was used mainly for the test
environment. Now we use a different logic to get the same result.
From now on it won't be possible to pass the option to avoid the log in
the development environment. I don't know a developer who's ever used
this option, though, and it can always be done using `> /dev/null`.
Calling `load_tasks` in several files made rails load the tasks several
times, and so they were executed several times when called.
Since the milestone migration can't be executed twice in a row (it would
fail with duplicated ID records), loading the tasks several times made
the milestone migrations task specs fail.
The db:dev_seed rake logs info as it progresses as information for the
developer. But that's not needed when ran from its tests file, and it
bloats the travis/rspec output with unnecessary information.
Now the task will always log info unless the rake task receives an
optional argument.
