New host module and fixed memory collector for OS X 10.9 Mavericks

Apple had integrated the WKdm algorithm to compress data in the RAM, in OS X 10.9 Mavericks.
Unused memory can be compressed to free more memory, without swapping.

I have tested this behavior on my MacBook Pro with 8 GB of RAM. Mac OS X can give 12 GB of memory to the system and to the applications, before starting swap on the hard drive/SSD! Just incredible.
During this process, the CPU occupation is higher.

You can read more about it on:
- http://www.apple.com/osx/advanced-technologies/
- http://terpconnect.umd.edu/~barua/matt-compress-tr.pdf

So, to do it, Apple had added new page types for the memory (see #85).
CentralReport can now analyse them and displays right data about memory.

I have added the "cr.host" module. It contains all code to determine the current host and to get information about it. It was previously in the "collector" module, which is destined to died in a next release.

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NB: Was #87 previously. Replaced by this new one: we must merge this branch in "develop", not in "master".