Adds a separate field to the node memory, "provisioned", which totals
the amount of memory provisioned to all VMs on the node, regardless of
state, and in contrast to "allocated" which only counts running VMs.
Allows for the detection of potential overprovisioned states when
factoring in non-running VMs.
Includes the supporting code to get this data, since the original
implementation of VM memory selection was dependent on the VM being
running and getting this from libvirt. Now, if the VM is not active, it
gets this from the domain XML instead.
Move all API calls to a new common function called call_api to
facilitate easier future changes. Use this function to implement API key
handling via request header value as well as integrate the request URI
generation and debug output handling.
Closes#65
Joshua Boniface