Remove unused files.

Refs #4962
Add cmake build files.

Refs #4962
Get version information from the icinga2.spec file.

Refs #4962
Update spec file.

Refs #4962
Install icinga2-enable-feature.

Refs #4962
Update file permissions for the scripts.

Refs #4962
Fix DESTDIR support.

Refs #4962
Install missing files.

Refs #4962
Change target name for the icinga2 binary.

Refs #4962
Set minimum version for flex.

Refs #4962