v1.2.0: Performance improvements and additional optional fields in response

Improvements (/find/worklogs):

• new optional parameter called "fields" which defines additional fields to return. Available fields are: comment, updated.
• querying worklogs now performed by plain sql search
• minor performance improvements

New features (/find/worklogsByIssues):

• summarize the worked seconds by issues between the given dates, for the given user(s)
• the returned issues can be filtered by a jql expression
• additional fields can be added by the "fields" parameter, just like in the jira api