Adds support for Floating IP

A quick search for the pattern:

```bash
# Total PUT methods
$ find . -name '*.java' -exec grep -H '@PUT' {} \; | wc -l
95
# Approximate number of PUT methods with a 404 fallback defined (after the PUT annotation)
$ find . -name '*.java' -exec grep -H '@PUT' -A4 {} \; | grep 404 | wc -l
22
# Approximate number of PUT methods with a 404 fallback defined (after the PUT annotation)
$ find . -name '*.java' -exec grep -H '@PUT' -B4 {} \; | grep 404 | wc -l
0
```

So, from the 95 put operations, only 22 use this pattern, and from those 22, all of them are OpenStack and Rackspace APIs, and just 1 method in Atmos.

Same number for the jclouds-labs providers:

```bash
# Total PUT methods
$ find . -name '*.java' -exec grep -H '@PUT' {} \; | wc -l
118
# Approximate number of PUT methods with a 404 fallback defined (after the PUT annotation)
$ find . -name '*.java' -exec grep -H '@PUT' -A4 {} \; | grep 404 | wc -l
11
# Approximate number of PUT methods with a 404 fallback defined (after the PUT annotation)
$ find . -name '*.java' -exec grep -H '@PUT' -B4 {} \; | grep 404 | wc -l
0
```
The pattern here is used in 11 calls, all them in the cloudsigma2 and cmdi providers (just 2 providers).

So it seems that the pattern is mostly used in the OpenStack APIs and *cloudsigma2*, and just in concrete places in the *cdmi* and *atmos* providers. The common pattern in jclouds is not to use that fallback in this kind of operations.