[Tilecache] Patch: fixes ImportError in our cases

[Gregor Mosheh]

Hi, all. I have two patches to contribute, and apparently sending them 
to the list is the preferred way of doing so.

Problem: The existing import statements in Service.py were causing 
ImportError exceptions when run from the command line. While a 
PYTHONPATH could have solved this, this solution makes the imports more 
robust when running from the command line, e.g. in tilecache_seed.py

This diff was from TC 2.01 but should apply to 2.04 as well.

--- Service.old.py      2008-08-09 11:28:35.000000000 -0700
+++ Service.py  2008-08-09 11:29:10.000000000 -0700
@@ -5,8 +5,12 @@
  class TileCacheException(Exception): pass

  import sys, cgi, time, os, traceback, ConfigParser
-from TileCache import Cache, Caches
-from TileCache import Layer, Layers
+try:
+    from TileCache import Cache, Caches
+    from TileCache import Layer, Layers
+except ImportError:
+    import Cache, Caches
+    import Layer, Layers

  # Windows doesn't always do the 'working directory' check correctly.
  if sys.platform == 'win32':