New import names in pydicom 1.0

[matthew-brett]

See: https://github.com/darcymason/pydicom/wiki/Porting-to-pydicom-1.0

Need wrapper something like:

try:
    import dicom as pydicom
except ImportError:
    import pydicom

try:
    read_file = pydicom.dicomio.read_file
except AttributeError:
    read_file = pydicom.read_file