Handle user-data compression with IO::Uncompress

[mguegan]

After some testing today, cloud_init() doesn't work anymore. It seems that retrieved user-data is now compressed.

This lazy fix should take care of that.

Note :
A better way to handle this case may be done directly on get_data() :

• add a check for compressed blob (on headers)
• handle the compressed data

[pyr]

Hey! thanks for this, since gunzip silently returns the string when data is uncompressed, this can safely go in. There's still the case of multipart user-data, but there's only so much you can do with just the tooling available in base :-)