git-template-library: log invalid option if any
get-template-library: do not dowload SPMA-based OS templates by default
- option --spma added to download them.
- fixes scdb#20
get-template-library: do not download templates for RC versions
* option --release-candidates added to explicitely download them
* Fixes #36
Merge pull request #37 from jouvin/get-template-library

get-template-library: do not download SPMA-based and RC OS templates by default