Nodepower plugin fix

After a call to ipmi_cmd, the current ipmi session needs to be closed by
making a call to 'ipmi_close' this will reset the state flow of the
ipmiutil library and leave it open for other components' use.

Added the missing call to ipmi_close
Nodepower plugin

Fixes #31
IPMI Plugin & nodepower plugin

The IPMI plugin tries to read the bmc credentials in an endless loop in
case it fails to read for some reason, and no other compute node tries
to send the bmc credential data. Fixes #35

The nodepower plugin uses the ipmi_cmdraw command to retrieve data from
the bmc. It needs to pass the length of the response buffer to the API
so that the library knows how much memory is allocated to it and can
pack the data accordingly. The current implementation does pass the
repose length. but it doesn't initialize the length, which could lead to
non deterministic results. Initialized teh lenght to 1024 to reflect the
size of the data buffer. Fixes #33

If the ipmi_cmdraw call in the nodepower plugin fails for some reason,
then the failure is currently being ignored and the responseData is
copied out and passed to the application. Added the code to handle a
return failure of the ipmi_cmdraw call.
Nodepower Plugin

Fixes #34
read_ein returns 0 on success or -1 on failure
changed control flow based on call_readein return value
Nodepower plugin

Changed the return values from -1 & 0 to ORCM_ERROR and ORCM_SUCCESS
Nodepower include and #define