Some cmake-related fixes for hypertable, sigar and moses

This patch deals with the cmake files in the project as follows:

- hypertable: current cmake file has 0.9.2.4 version hard-coded into it; as per [hypertable guidance](http://hypertable.com/documentation/installation/quick_start_standalone#step-3---set-current-link) the user is expected to create a symbolic link to current version:

```Shell
cd /opt/hypertable
ln -s $VERSION current
```
- sigar: by manually building the library one gets libsigar.a on ubuntu, for example; adding sigar name helps cmake find the library
- moses: when building out of source git repository will not be reachable; adding WORKING_DIRECTORY works both for in source and out-of-source builds