Add information on virtualenv usage

This patch also adds link to Python Package Index (like for doc8
package), drops no longer necessary privilege elevation and fixes minor
spacing issues.

Issue-ID: DOC-502
Change-Id: I55a583bf05a731371008d9cfb55cbfa2e2ad3a77
Signed-off-by: Pawel Wieczorek <p.wieczorek2@samsung.com>
1 file changed