Print inner startup exception cause to stderr

Startup exceptions should have the cause printed to the stderr. Currently the full stack trace is printed to the log file, and only startup exception to the stderr - looking like this

  Exception in thread "main" com.google.enterprise.adaptor.StartupException: Failed to start application.
    at com.google.enterprise.adaptor.Application.main(Application.java:555)
    at com.google.enterprise.adaptor.AbstractAdaptor.main(AbstractAdaptor.java:61)
    at com.google.enterprise.adaptor.database.DatabaseAdaptor.main(DatabaseAdaptor.java:271)

Especially when there are some other warnings printed out to stdout/stderr, this can be confusing, so including also the inner exception in the message

src/com/google/enterprise/adaptor/Application.java

@@ -555,13 +555,16 @@ public static Application main(Adaptor adaptor, String[] args) {
     } catch (InterruptedException e) {
       Thread.currentThread().interrupt();
       log.log(Level.INFO, "Application startup interrupted.", e);
-      throw new StartupException("Application startup interrupted.");
+      throw new StartupException(
+          "Application startup interrupted. " + e.toString());
     } catch (IOException e) {
       log.log(Level.SEVERE, "Failed to start application.", e);
-      throw new StartupException("Failed to start application.");
+      throw new StartupException(
+          "Failed to start application. " + e.toString());
     } catch (RuntimeException e) {
       log.log(Level.SEVERE, "Failed to start application.", e);
-      throw new StartupException("Failed to start application.");
+      throw new StartupException(
+          "Failed to start application. " + e.toString());
     }
   }