also db initialization has been moved before other imports, so that not
it is possible to load collections in Storages

fix avatar handling and create schema
filter permissions for containers in handlers

use tempdir custom module instead of tempfile
fail with 400 when ObjectIds are not valid
check existing schemas against a list at startup
add json schema draft 4 specification
give a more detailed error message for keys mismatch
remove upload method in core.py = dependencies (util.upload_ticket +
json schema)
remove search call + method = schema