add method for getting owner templates

[surzm]

• getMyTemplates

[sendpulse]

Hi, @surzm! We appreciate your efforts, but there are some remarks.

If you want your changes to be approved please rework the method getTemplates:

• add string parameter owner
• add parameter validation only for values: 'me', 'sendpulse' or empty (see documentation https://sendpulse.com/integrations/api/bulk-email#template-list)
• make request more flexible: with proper parameter owner or without if value is not presented