CC-BY licenses - add optional tags where missing

[jlovejoy]

fixes #1548

Signed-off-by: Jilayne Lovejoy

[jlovejoy]

This should include updates to all CC-BY and CC-BY-SA variants except the Japanese language one, as I wasn't confident of placement

[xsuchy]

+1

[xsuchy]

But tests are failing:

 The following warning(s) were identified:
	Test for license CC-BY-SA-3.0-AT failed: Test for license ID CC-BY-SA-3.0-AT failed due to difference found Normal text of license does not match starting at line #5 column #4 "gegenstand" when comparing to template text " >

DER GEGENSTAND DIESER LIZENZ (WIE UNTER „SCHUTZGEGENSTAND" DEFINIERT) WIRD UNTER DEN BEDINGUNGEN...".  Last optional text was not found due to the optional difference: 
	Normal text of license does not match starting at line #1 column #9 "commons" when comparing to template text "Namensnennung - Weitergabe unter gleichen Bedingungen 3.0 Österreich"

[swinslow]

Tests are failing due to accidental extra > in CC-BY-SA-3.0-AT:

</optional>>

I'll submit a fix to address this.

[swinslow]

Should be fixed in bc28bf0; I'll merge after tests pass.