Fix code format.
Fix feature description and clarify sample output.
Fix code format.
* Rename get_trema_process_from_name to get_pid_by_trema_name
* Mark get_trema_process_from_name as deprecated
* Rename get_trema_process_from_name to get_pid_by_trema_name
* Change example names to meaningful names
Rename Trema::Logger -> Trema::DefaultLogger (refs #264).

Formerly, if a programmer tries to use Trema combined with ActiveSupport library, trema run failed with "Logger is not a class" error. This is because ActiveSupport defines Logger class at the top level, and trema run includes Trema module at start-up, therefore a type-mismatch between the definition of Trema::Logger and AR's Logger occurred.

This fix renames Trema::Logger as Trema::DefaultLogger to avoid the name conflict.
Revise .feature description.
Merge remote-tracking branch 'upstream/develop' into develop
Merge branch 'fix_read_pid_check' into develop