Batch - space added to content-type: application/http

[bpreissler]

In the file pyodata/v2/service.py in line 46
lines.extend(('Content-Type: application/http ', 'Content-Transfer-Encoding:binary'))
There is an unnecessary space after the Content-Type header. While SAP ABAP seems to ignore that an API Gateway I have to use does fully validate and with that space it is an invalid content type.

[bpreissler]

Sry, overlooked #285