Fix version generation
Fix version generation

This adds version generation in a more portable manner, requiring only
Git for the most basic meta-data. This allows us to generate versions
properly on Windows without requiring a full GNU coreutils installation

Change-Id: Ic10b9a4a76071c8b3cbeb4a8032ecb6ca5a61c31
Reviewed-on: http://review.couchbase.org/43420
Tested-by: Mark Nunberg <e7d42768707bf23038325b0b68d4b577e5f6064a@haskalah.org>
Reviewed-by: Subhashni Balakrishnan <7129c8e37b832c7bd362ff375532d24b98ef5162@gmail.com>

mnunberg/libcouchbase,signmotion/libcouchbase,maxim-ky/libcouchbase,signmotion/libcouchbase,PureSwift/libcouchbase,avsej/libcouchbase,kojiromike/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,signmotion/libcouchbase,couchbase/libcouchbase,mody/libcouchbase,couchbase/libcouchbase,avsej/libcouchbase,couchbase/libcouchbase,mnunberg/libcouchbase,PureSwift/libcouchbase,mnunberg/libcouchbase,mody/libcouchbase,PureSwift/libcouchbase,avsej/libcouchbase,kojiromike/libcouchbase,senthilkumaranb/libcouchbase,maxim-ky/libcouchbase,senthilkumaranb/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,senthilkumaranb/libcouchbase,avsej/libcouchbase,kojiromike/libcouchbase,maxim-ky/libcouchbase,avsej/libcouchbase,avsej/libcouchbase,mnunberg/libcouchbase,senthilkumaranb/libcouchbase,mnunberg/libcouchbase,avsej/libcouchbase,mody/libcouchbase,PureSwift/libcouchbase,signmotion/libcouchbase,mody/libcouchbase,maxim-ky/libcouchbase,kojiromike/libcouchbase