Merge pull request #10 from sualk/for-upstream

Two patches (http response, item caching)
Use old laststoragesync mode for API version 1
Return error message instead of hanging sync for huge notes
Use default libcurl SSL verification
Fix intermittent upload error due to duplicate relation ids
Properly clear memcached tx state when committing with empty queue
Along with 73595d1156, fix and test Zotero-Write-Token
Check write token for any write method
Fix new link attachment with itemKey specified
Don't cache download responses

* Don't cache download responses in Amazon S3
* Remove AWS-SDK
Move login data to master DB

* move password field to master.users
* disable login with e-mail address
* disable md5 hashed passwords
* no need to update username, since it is no longer stored in two different places
No login via session cookie
All user accounts are only in master DB

* Do not add users from WWW DB
* All users are valid
Move user privacy settings to master DB
Only check personal quota
Remove unused DB classes
always use $_SERVER['REMOTE_ADDR'], even if it contains a private ip

this fixes an error if only private IPs are used
Add script to setup a minimal database
Add script to add new users
Add init-scripts to start zotero processors