vty: Use generic 'end' and 'exit' commands

Add bsc_install_default() and replace all install_default()

This patch adds bsc_install_default() which calls install_default()
and add 'exit' and 'end'. All other calls to install_default() are
replaced by calls to bsc_install_default().

Since 'exit' and 'end' are now added automatically to each node, the
explicit registrations of these commands are removed by this patch,
too.

The related tests succeed now without work-arounds (except for the
'config' node itself which is part of libosmocore).
diff --git a/openbsc/tests/vty_test_runner.py b/openbsc/tests/vty_test_runner.py
index e91d018..5af59a9 100644
--- a/openbsc/tests/vty_test_runner.py
+++ b/openbsc/tests/vty_test_runner.py
@@ -74,11 +74,6 @@
         except BaseException as e:
             sys.stderr.write('Expected and ignored failure: %s\n' % (str(e))) 
 
-    def notIgnoredTest(self):
-        sys.stderr.write('Going to ignore the next assertion(s) due to known bugs\n')
-        return False
-
-
     def _testConfigNetworkTree(self):
         self.vty.enable()
         self.assertTrue(self.vty.verify("configure terminal",['']))
@@ -128,10 +123,7 @@
         self.assertEquals(self.vty.node(), 'config-smpp')
         self.ignoredCheckForEndAndExit()
         self.assertTrue(self.vty.verify("exit", ['']))
-        if self.notIgnoredTest():
-            self.assertEquals(self.vty.node(), 'config')
-        else:
-            self.assertTrue(self.vty.verify("configure terminal", ['']))
+        self.assertEquals(self.vty.node(), 'config')
         self.assertTrue(self.vty.verify("exit", ['']))
         self.assertTrue(self.vty.node() is None)
 
@@ -185,20 +177,14 @@
         self.ignoredCheckForEndAndExit()
         self.assertTrue(self.vty.verify("msc 0", ['']))
         self.assertEquals(self.vty.node(), 'config-msc')
-        self.ignoredCheckForEndAndExit()
+        self.checkForEndAndExit()
         self.assertTrue(self.vty.verify("exit", ['']))
-        if self.notIgnoredTest():
-            self.assertEquals(self.vty.node(), 'config')
-        else:
-            self.assertTrue(self.vty.verify("configure terminal", ['']))
+        self.assertEquals(self.vty.node(), 'config')
         self.assertTrue(self.vty.verify("bsc", ['']))
         self.assertEquals(self.vty.node(), 'config-bsc')
-        self.ignoredCheckForEndAndExit()
+        self.checkForEndAndExit()
         self.assertTrue(self.vty.verify("exit", ['']))
-        if self.notIgnoredTest():
-            self.assertEquals(self.vty.node(), 'config')
-        else:
-            self.assertTrue(self.vty.verify("configure terminal", ['']))
+        self.assertEquals(self.vty.node(), 'config')
         self.assertTrue(self.vty.verify("exit", ['']))
         self.assertTrue(self.vty.node() is None)