Add tools/delete_activities

Check that issue_id exists when a 500 internal server error is receiv…

…ed by Redmine

Add check_issues_exists option

Merge branch 'password_auth'

Update changelog

Adding possibility of using more verbose Hamster entries ("Fix #132: …

…nothing works" for example), Adding output to user, Refactoring config file sections, Adding output in case of server errors (due to malformatted requests) Updating README