Added sections and articles for help center
Merge with Interfaces
Added Async methods on HelpDesk sections articles
Change type of date/time fields from 'string' to 'DateTimeOffset'
Add unit test for creating a ticket with DueAt setting
Add check for CreatedAt, UpdatedAt to ticket creation test
Some resources where not disposed 

dataStream and response were not disposed, this could crash when we upload many files
Add CustomFieldOptions.Id property
Add UnitTest to update TicketField.CustomFieldOptions
Remove nullabe designation from DueAt. It causes a build error, and is unnecessary as string is a nullable type.
Add HelpCenter Category models
Correct HelpCenter.Categories namespace
Add HelpCenter Categories requests
Add locale and tests for HC categories
Merge irq's article and section features
Formatting fix
fixed Ticket DueAt
erged ggrossmans PR
fixed ticket export
Merge branch 'master' of https://github.com/peteallen/ZendeskApi_v2 into peteallen-master
got branch to compile
merged and fixed ticket metrics test
Merge branch 'pr/102'