This function returns list of sections from specified INI file.
It is needed for I7938f26015d953efdf720774b5ad2cee4068ac90.
'iniget_sections' is needed for automatic node enrollment to
Ironic from INI syntax file.
Change-Id: I52a69ad3bc8fc528e7f20e6b03a98f327acaaa74
Implements: blueprint ironic-ml2-integration