show default image when avatars fail to load
add missing avatar classes
fix height
fix `avatar_url` macro
handle cached images
use another approach that also works in IE
only localize by language, dismiss the country code
fix `{n} Members` message

For numbers greater than 999 the `.replace(str(community.nmembers), ...)` hack would not have worked.
bring back JS tests

They were turned off to ease development.
simplify messages
fix credit card page
small shortcut
minor simplifications
Merge pull request #2639 from gittip/fix-i18n

Fix i18n
Bump version to 15.0.5
Bump version to 15.0.5-dev
Merge pull request #2608 from gittip/no-broken-avatars

No broken avatars
Bump version to 15.0.6
Bump version to 15.0.6-dev
Merge branch 'master' into support-gittip