pylib: more improvement in general function for attributes management
commands: use rocks.db.helper class to manage DB interaction
commands: move a lot of function in rocks.db.helper
commands: update all the rocks command to use the new attribute table

now all the rocks command use the new generic Attributes table
tests: full siute of tests for the attriubtes command line
commands: remove some useless code
commands: remove variuos code referring to old attribute tables
commands: remove variuos code referring to old attribute tables
commands: remove variuos code referring to old attribute tables
commands: remove variuos code referring to old attribute tables
commands: remove variuos code referring to old attribute tables
commands: remove dhcp report code referring to old attribute tables
commands: remove variuos code referring to old attribute tables
commands: remove code referring to old attribute tables (insert-ether)
commands: remove variuos code referring to old attribute tables
pylib sql: creation of new calindex entry is now in clusterdb

This will be fixed soon in the following commits but for now
simply move the creation of the catindex in clusterdb insert
since we need to add a host attribute there.
commands: fix several typos
pylib: remove Abort from helper class
node.xml: "UseDNS no" cannot be appended to sshd_config

since now we are using a Match directive at the end of the
sshd_config we can not have more global directive after the
Match section.

UseDNS must be activated before the Match if used
pylib: make database connection customizable