Add handling for class "Item" property "text" being null

[chris-jelly]

Disclaimer

First pull request. Roast me.

Fixes #1

Problem

In the Item class, the init method was encountering an error on assigning self.text with values[1] when it was null, as it was calling strip on a null value

Why does the problem exist

I do not know what changed (if anything) in the sqlite schema to cause this new issue.

Solution

Adding a quick check to only set the property if the value is not none fixes the immediate issues, however the self.text property must exist for line 141, so I added an else clause to manually set to None.

[eliascotto]

Thanks, resolved with new version.