Log work entry default time period should be configurable

When logging work time, if the user does not enter a specific qualifier like h, d, etc..., then it defaults to minutes. The default is poor in many cases. Almost all of the time entered by our users is in hours. We need a mechanism to specify the default time period so we can change in to hours. Ideally, this could be done in the UI, but it would be sufficient for us to be able to configure it in the jira-application.properties file.