$platform  should be lowercase to avoid FileNotFoundException

Without this fix, the process crash on Linux while working fine on OSX

Signed-off-by: remi-parain <rparain@ubidreams.com>
"maven-war-plugin" dependency should not be mandatory.
The build should not crash if the dependency is missing.

Signed-off-by: remi-parain <rparain@ubidreams.com>
Merge pull request #69 from remi-parain/master

missing toLowerCase() call + missing  null test on plugin dependency