configurable cookie file.

see #173

added configurable curl user-agent string option.

see #171

Use full namespaces in doc blocks

see #170

implement version create, modify, delete

see #164

add setter method for duedate

see #162

update isssue' labels

New feature: add or remove issue's label
See #116

attachment service

New Feature: Attachment Service, See - #159

• https://github.com/lesstif/php-jira-rest-client#attachment

add PriorityService

see #155

reporter field is nullable.

See #151

fixed bug - security scheme mapping

• fixed (#148 )
• added json mapping unit test