Remove null=True from CharFields, TextFields, ...

... and EmailField

Conflicts:
	cyder/core/system/models.py
Join short lines
Add schema migrations for e3cf392
Duplicate systems no longer cause test1_delete_basic to fail incorrectly.
Merge pull request #23 from drkitty/removenull2

I've tested these changes and found that it created no new errors. I'm approving this pull request for merge.
Test details:
```
< FAILED (errors=99, failures=215)
---
> FAILED (errors=77, failures=223)
```