Added integration tests for importing from files.
Merge branch 'master' into import-export
Added stub function.
Everything is good except for links.

For some reason the tests are failing when it comes to the links. I'm
not sure how I'm supposed to pass link information, probably as a
list...
Initial pass completed. links are working.

Messy version of import done.
Renaming and code consolidating

Grouped the if i: blocks together.
Renamed so I don't have so many 'attribute' variables.
Fixed error.

Tests caught this.
Added a bunch of descriptive comments. and a few todos

not sure how to handle regex's as they could vary based on project
requirement format.
Working on tests for new code
Allowing custom Item IDs.
Added a missing comment.
Added csv and tsv support

re-worked xlsx import to use same functionality as tsv and csv imports
Fixed issues with .tsv files
Made changes due to Jace's github comments
Added prefix guarding to bypass an annoying bug for now

changed regex to be a split for links.
Modified tests to show that the core issue to importing when deleting
and re-creating an issue is through the call to document.items.
Added cache clearing to document and item.
Merge branch 'cache' into import-export
Merge branch 'master' into import-export
Code cleanup.
Fixed item-document caching issue.