add "hma" agent for external monitoring host nodes and trigger HA operation.
make original HA trigger obsolete.
add basic monitoring condition primitives.
split json rpc client with zabbix authentication code from drivers/zabbix.rb as helper module.
add monitoring handler to poll status from Zabbix server.
change condition AST design.
add sized array to store fixed size of monitoring result history.
add plain DSLProxy class to avoid method confliction from condtion DSL.
add ntimes continuous status checker for HA monitor DSL.
add And node.
send evacuate_from request after the host node failure.
cleanup unused lines eventually.
Merge branch 'master' into ha-monitor-agent
Merge pull request #400 from axsh/split-conf-classes

Split conf classes
hva: remove code duplication in booting instance process.
Enabled shared example for instance with ip leases
Allow the database uri to be read from both dcmgr.conf and nwmongw.conf
Got rid of that #$%@ copy pasted code that the natbox used to load its config file.
kvm: constrain listen port range for qemu to avoid OS local port range.
kvm: set range values from separate parameters. retire original string range parameter.