Add to hasSessionStorage check to make sure we can actually write to sessionStorage before enabling.
Changing some logic around so we check for writability in setState() while still preserving the ability to read from sessionStorage if we can find data there.
Add this to fn call.
Add comment related to why we clear out session storage when writing to cookie.
Merge pull request #89 from zimmi88/storageErr

Fix sessionStorage exceeds quota error in Safari