Only write something when the output string is non-empty.

Otherwise we get useless trailing newlines in our output.

Main.py

@@ -46,6 +46,7 @@ def write(p_file, p_string):
     if not p_file.isatty():
         p_string = escape_ansi(p_string)
 
+    if p_string:
         p_file.write(p_string + "\n")
 
 class CLIApplication(object):

test/CommandTest.py

@@ -9,7 +9,9 @@ class CommandTest(unittest.TestCase):
         self.errors = ""
 
     def out(self, p_output):
+        if p_output:
             self.output += escape_ansi(p_output + "\n")
 
     def error(self, p_error):
+        if p_error:
             self.errors += escape_ansi(p_error + "\n")