Fix urls under /sky to work again

Fix urls under /sky to work again

Turns out that the /sky mapping to the gen
directory was interfering with our new pattern
of mapping the actual /sky directory.

So now we use a more restrictive mapping pattern
of only mapping /sky/services, similar for
/mojo/services and /mojo/public.

Fixed an exception of not finding _sky_server
when a custom sky_server was already running.

R=abarth@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/b58fdff403eb92ba0207e38b529d7a96e28c5954

[abarth-chromium, 2014-10-31 18:43:39]

LGTM

https://codereview.chromium.org/692163002/diff/1/sky/tools/sky_server
File sky/tools/sky_server (right):

https://codereview.chromium.org/692163002/diff/1/sky/tools/sky_server#newcode72
sky/tools/sky_server:72: '/mojo/public': {
/mojo/services

[ojan, 2014-10-31 18:44:45]

Should we keep apache_http.py in sync with these changes?

[eseidel, 2014-10-31 18:46:06]

Committed patchset #1 (id:1) manually as
b58fdff403eb92ba0207e38b529d7a96e28c5954 (presubmit successful).