Integrate pip into python commandlet

[jan-vcapgemini]

As a python user I expect pip to be installed into my python directory.
Currently we move the pip.py script into a new folder software/pip which can be confusing for python users and will result in compatibility issues with older versions of python.

We need to get rid of pip as a separate commandlet and make sure that each version of python will install its own pip within its installation directory.
We also need to get rid of the ide-urls for pip and disable the cached download as mentioned in: #1170

[CREITZ25]

#1170 shows the correlations between Github versions and software versions of pip, and which pip should be used for which Python

[hohwille]

For the record: We initially had pip integrated in python and later had to extract it to its own commandlet.
The discussion can be found in #839