Normalize redis cache key and add peatio prefix
Setup redis cache expired time to 24 hours.
Merge branch 'master' of https://github.com/peatio/peatio
log exceptions in cache book thread
log exceptions in order processor thread
Simplify the password format checking.

1. The minimum length is set to 6. Because a lot of people's debit cards
use 6 length passwrod. They may wanna use the same with Peatio.
2. Remove the checking for the format of a password. We just give suggestion.
Optimize the transfer comment display.
To make sure user know to write the sn number in the back transfer comment.
Merge pull request #115 from peatio/simplify_the_password_format_check

Simplify the password format checking.
Merge pull request #116 from peatio/optimize_the_transfer_comment_display

Optimize the transfer comment display.
Merge branch 'master' of https://github.com/peatio/peatio