Change the format of the version string

[lferrandis]

Currently, the format of the version string is x.y.z and it's provided by the autotools.

We can change the format in debug and/or release to add the commit sha1 on which the component is builded: x.y.z-sha1

We should use the short sha1 format, not the long one.

[emanueleaina]

A common convention is to prefix the git hash with a g, as in 1.2.3-gbadcafe, to allow for other notations (eg. 1.2.4-alpha1 or similar).