add Mb, Gb, Mb/s, Gb/s to network rule
transfer NetworkAlert to non-MetricItemConfig
add rule for each business MetricItemConfig
fix bugs which can not insert config when all fail
change td width for manipulation button; hide allBusinessRule page
fix bugs which throw exception when remove an object while looping
modify the manager
merge newest code
Merge pull request #353 from leonindy/master

add unit to NetworkAlertConfig, remove itemConfig-dependency from NetworkAlert, add rule-config page for business items, fix serveral bugs