Update common.py

Adjusted minimal order size for btc_eur and btc_rur
Merge pull request #29 from Jazzer9F/patch-1

Thanks!
Updated minimal order size for btc_eur and btc_rur.
Decode page text and unescape HTML entities before parsing (fixes broken HTML entity handling in comments).
Fixed show-chat example so that it doesn't fail if no reserve values are available (are these permanently gone now?).
Added donation address.
Merge pull request #2 from alanmcintyre/master

Update