adding functional test to cover same issue

functional test writes and read a large object to exercise
code that calls drop_cache after reading 1MB of data

Signed-off-by: Thiago da Silva <thiago@redhat.com>
Merge branch 'GET_failure' of github.com:thiagol11/swiftonfile into GET_failure
removing unused time module

Signed-off-by: Thiago da Silva <thiago@redhat.com>