Originally the App uses org.dharkael.Flameshot in D-Bus.
Since we have moved the project under organization, the
name we are using now should be org.flameshot.Flameshot.
This need to be kept unified across the whole project.
This fixes D-Bus invocation problem and should fixes: #850 .
This commit updates some URLs used within the project:
* Update README.md logo URL so that the flameshot logo can be
shown properly.
* Update metadata used in data/debian/ directory to make
placeholder Debian packaging working again.
* Some other quick URL fixes.
These fixes are not meant to be exhaustive and more work is
needed.