version is not set in CMake when pmemkv is downloaded as a zip

[lukaszstolarczuk]

Environment Information

pmemkv downloaded as a zip, e.g. from github

Actual behavior:

VERSION variable is not set, hence make package will create a package with empty "version=" parameter and other apps using our library won't be able to check version of our library.

Expected behavior:

VERSION is set somehow

Details

1. we can use zip name to establish version - GH prepares zip called "pmemkv-master" for master branch
2. we can hardcode recently released version, like we do in libpmemobj-cpp