Add title to tests.

slapos/rebootstrap/default.txt

+Default invocation
+------------------
+
 >>> import sys
 >>> mkdir(sample_buildout, 'recipes')
 >>> write(sample_buildout, 'recipes', 'setup.py',

slapos/rebootstrap/eggsupport.txt

+Support for additional eggs
+---------------------------
+
 >>> import sys
 >>> mkdir(sample_buildout, 'addegg')
 >>> write(sample_buildout, 'addegg', 'setup.py',

slapos/rebootstrap/extensionsupport.txt

+Support for extensions
+----------------------
+
 >>> import sys
 >>> mkdir(sample_buildout, 'recipes')
 >>> write(sample_buildout, 'recipes', 'setup.py',

slapos/rebootstrap/partsexists.txt

+Support of cases when reboostrap part exists
+--------------------------------------------
+
 >>> import sys
 >>> mkdir(sample_buildout, 'recipes')
 >>> write(sample_buildout, 'recipes', 'setup.py',

slapos/rebootstrap/upgrade.txt

+Support of upgrade
+------------------
+
 >>> import sys
 >>> mkdir(sample_buildout, 'recipes')
 >>> write(sample_buildout, 'recipes', 'setup.py',

slapos/rebootstrap/withownpython.txt

+Support of own python path
+--------------------------
+
 >>> import sys
 >>> mkdir(sample_buildout, 'recipes')
 >>> write(sample_buildout, 'recipes', 'setup.py',