Add .venv and subunit.log to .gitignore
Add .venv and subunit.log to .gitignore

If we run unittests there are appear dir .venv and file subunit.log
So, add these files to gitignore.

Change-Id: I64c400d1333e12b87da7fcd2c64772964e3f1b3c

sniperganso/python-manilaclient,sniperganso/python-manilaclient