[HatoholArmPluginBase] Rename a method to improve readablity.

onReceivedFetchItem ->
onReceivedReqFetchItem
[HapProcessStandard] Clean up.
[HapProcessStandard] Add a parameter to skip to setup timer.
[HapProcessStandard] Extend startAcquisition so the caller can change the main process.
[HapProcessStandard] Rename a member function because it's is used only for callback.
[HapProcessStandard] Fetch items on a GLib event loop.
[HapProcessStandard] Follow the rename of the base class's virtual method.
[[HapProcessCeilometer] Implement basic code to get items from ceilometer.
[HapProcessCeilometer] Collect useful items only.
[HapProcessCeilometer] Remove a debug print.
[HapProcessCeilometer] Set 'N/A' to a previous value.
Merge pull request #668 from project-hatohol/item-ceilometer-2

Item ceilometer 2