A simple integration to OpenStack Swift.

Added a new backend 'swiftstore'. This backend store files
to OpenStack Swift object storage.

### Pre-requirement
Install the python-swiftclient
```
pip install swiftclient
```

### Configuration
modify ini file to use swift backend.
```
# OpenStack Swift storage:
ofs.impl = swift
ofs.os_auth_url = http://localhost:5000/v2.0
ofs.os_user = admin
ofs.os_passwd = admin
ofs.os_tenant = admin
```

### Running the unit test
It needs openstack swift running.
Fill the test.ini as following
```
[ofs]
ofs.os_auth_url=http://localhost:5000/v2.0
ofs.os_user=admin
ofs.os_passwd=admin
ofs.os_tenant=admin
```