tox.ini warning fix
tox.ini warning fix

This fixes the follwing warning thrown onto console
  - Invalid -W option ignored: invalid action: '"ignore'
  - /bin/mkdir: cannot create directory .tox/palmetto/tmp: File exists

Resolves openbmc/openbmc-test-automation#106

Change-Id: I2b3e6ff5222564c61a741da62b725a78e8304052
Signed-off-by: George Keishing <bef0a9ecac45fb57611777c8270153994e13fd2e@in.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation