Move python-keystoneclient to "extras"

This should make it more clear to users that they may want to install
it.

Change-Id: I8bb4f3eba1fc6d2b7b23c3bd51663678e755a69e

setup.cfg

@@ -32,6 +32,10 @@ scripts =
 data_files =
     share/man/man1 = doc/manpages/swift.1
 
+[extras]
+keystone =
+    python-keystoneclient>=0.7.0
+
 [entry_points]
 console_scripts =
     swift = swiftclient.shell:main

test-requirements.txt

@@ -3,6 +3,5 @@ hacking>=0.10.0,<0.11
 coverage>=3.6
 mock>=1.2
 oslosphinx
-python-keystoneclient>=0.7.0
 sphinx>=1.1.2,<1.2
 testrepository>=0.0.18

tox.ini

@@ -12,6 +12,7 @@ setenv =
 
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
+       .[keystone]
 commands = sh -c '(find . -not \( -type d -name .?\* -prune \) \
            \( -type d -name "__pycache__" -or -type f -name "*.py[co]" \) \
            -print0; find . -name "*.dbm*" -print0) | xargs -0 rm -rf'