two protos for common operations: Crudable and Convergeable

Currently Blobstore, Metastore and Bucketstore provide protocols
sharing some signatures. Converge to common protocols defined
in io.pithos.store instead.
adapt schema to new protocols
prepare atomm based stores for integration tests
use crudable for keystore as well
switch keystore to behave as a map through clojure.lang.ILookup
add full system creator
look up keys in the right place
provide a handler builder to facilitate tests
this went in too fast
log during tests
log exception when triggered during signature
enable system tests
enable add expected ACL test
put & remove bucket test
add put object test
simplify tests
add tests for reporters
update protocol documentation accordingly
Merge pull request #37 from exoscale/feature/standard-protos

two protos for common operations: Crudable and Convergeable