Add status badge of latest CI run to the readme file.

+Latest CI Status:
+Master [](https://gitlab.com/mojo42/Jirafeau/commits/master)
+Next Release [](https://gitlab.com/mojo42/Jirafeau/commits/master)
+[All Branch Builds](https://gitlab.com/mojo42/Jirafeau/pipelines?scope=branches)
+
## Main features
- One upload → One download link & one delete link