v0.15: Add volume state filtering back

It looks like trying to delete volume in any state triggers some race condition
in cinder, leading to undeletable volumes in reserved state.

v0.14: Allow garbage collector to delete volumes in any state

In some cases, volumes remained stuck in creating or reserved state.

v0.12

Logging refactoring

v0.11

Improve garbage collector logging

v0.10

Implement floating IP garbage collection

v0.9: Progate our current context to gophercloud

This helps cleaning up resources in case of timeout and might as well solve a
goroutine leak.

Closes #1.

v0.8

Fix a bunch of linter errors

v0.7

Improve memory usage of the object store test.

v0.6

implement io.Seeker interface to prevent gophercloud from buffering f…

v0.5

Rename -internal-network flag for consistency