Missed a couple of dots

IPython/nbconvert/exporters/latex.py

@@ -37,7 +37,7 b' class LatexExporter(TemplateExporter):'
     """
 
     def _file_extension_default(self):
-        return 'tex'
+        return '.tex'
 
     def _template_file_default(self):
         return 'article'

IPython/nbconvert/exporters/slides.py

@@ -25,7 +25,7 b' class SlidesExporter(HTMLExporter):'
     """Exports HTML slides with reveal.js"""
     
     def _file_extension_default(self):
-        return 'slides.html'
+        return '.slides.html'
 
     def _template_file_default(self):
         return 'slides_reveal'