Create logs model, controller and view. (Fix #1, #4)
Create LogFile. (Fix #6)
Add log_files controller. (#15)
Forward pos when many logs are exist. (#17)
Call save_tails before Log#index
Add feature to paginate. (#19)
Add index_grouped_by_tags view in LogsController. (#13)
Add insert_string_to_file. (#14)
log_files#limit_of_skip is moved to db column. (#18)
Modify some configuration.
Merge branch 'develop'