Re-implement more efficient GetBust

Was lost in a merge at a2049be03ac5adf025f645815c70d8d9b1316425
Merge pull request #111 from minotar/fastdraw

Faster drawing function
Fix formatting in cache_off.go
Usernames to lowercase

By normalizing the usernames we ensure that they only appear in cache
once.
Merge branch 'master' into fix-bust-efficient
use CarefullyPut in cache_redis when dealing with the pool
Reduce duplication in GetBust/GetBody
Put 1.8 Skin check in function
Use alpha matte for helm
Fallback to S3 when Mojang fails

Requires https://github.com/minotar/minecraft/pull/4 (or variation)
Only lowercase cache usernames

If we may fallback to S3 we need to keep the correct case.
Merge pull request #114 from minotar/helm-fix

Use alpha matte for helm
Merge pull request #113 from minotar/patch-lowercase-username

Usernames to lowercase
Merge pull request #115 from minotar/patch-fallback-s3

Fallback to S3 when Mojang fails
Upping version
Upping
Display skin source in log
Merge pull request #106 from mediocregopher/radix-pool-defer

use CarefullyPut in cache_redis when dealing with the pool
Show cached if we don't have a source
Merge branch 'master' of github.com:minotar/imgd