oneliners for waitFor()
fix outputstream not closed
Created Apps.sourcesAvailableIn() utility method
Allows to override restx mode when app name is given to `app run` *and* sources are available in the restx app
Removed boilerplate code with checkPresent() call
DownloadOptions being immutable with ImmutableList instead of plain List
Fixing potential NPE when guessAppClassnameFromSourcesSupplier() returns null-wrapped supplier
Fixed restx typo