Added Jira ServiceDesk support

[igor-pavlenko]

Added following API methods support (it doesn't break previously added methods):

• create_customer() Creates a customer that is not associated with a service desk project.
• service_desk_info() Returns runtime information about JIRA Service Desk.
• create_organization() Creates an organization
• delete_organization() Delete organization
• organization() Get an organization for a given organization ID
• organizations() Returns a list of organizations in the JIRA instance.
• add_users_to_organization() Add users to organization
• remove_users_from_organization() Remove users from organization
• get_users_from_organization() Returns a list of users in organization.
• service_desks() Get a list of ServiceDesk Resources from the server
• service_desk() Returns the service desk for a given service desk Id.
• create_request() Create a new customer request and return an issue Resource for it.
• request() Get an issue Resource from the server.
• my_customer_requests() Returns all customer requests for the user that is executing the query.
• request_comments() Returns all comments on a customer request, for a given request Id/key.
• servicedesk_attachment() Add attachment (from RequestTemporaryAttachment) to request
• attach_temporary_file() Create temporary attachment file
• request_types() Returns all request types from a service desk, for a given service desk Id.
• request_type() Returns a request type for a given request type Id.
• request_type_by_name() Return request type id by it name

All method covered with tests.

[codecov-io]

Codecov Report

Merging #371 into develop will increase coverage by 2.14%.
The diff coverage is 73.94%.

@@             Coverage Diff             @@
##           develop     #371      +/-   ##
===========================================
+ Coverage    47.94%   50.09%   +2.14%     
===========================================
  Files           10       10              
  Lines         2484     2651     +167     
  Branches       461      492      +31     
===========================================
+ Hits          1191     1328     +137     
- Misses        1150     1153       +3     
- Partials       143      170      +27

Impacted Files	Coverage Δ
jira/client.py	52.57% <70.05%> (+2.11%)	⬆️
jira/resources.py	66.32% <92.68%> (+2.76%)	⬆️

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[ssbarnea]

This is adding a lot of code to a class that is already really big and i am wondering if it would not worth to add a Desk class which exposes its instance automatically as "desk" attribute on Jira() objects. So people will be able to do j.desk.create_case() instead of "j.create_case".

This will keep the namespace clear and also allow you to put all the code related to desk in a separate file.

Please do not start to implement these changes until we don't get some feedback from someone else. Maybe they have better ideas.

[asqui]

Definitely agree with @ssbarnea that it would be a good idea to segregate this code off to prevent the JIRA class growing too monolithic. This seems like a separate area of functionality and a nice boundary on which to segregate.

[ssbarnea]

Closing this work needs to be rebased on master. Please feel free to create new PR, preferably splitting the work in multiple ones. It would be much easier to get small reviews in than bigger ones.