Disable --pre flag in tox installs to fix environment recreation.

Remove an old hack for monotime package.

tox.ini

@@ -23,6 +23,11 @@ changedir = {toxworkdir}
 # PYTHONPATH)
 #environment = PYTHONPATH=
 
+# tox 1.6 passes --pre to pip by default, which currently has problems
+# installing pycurl and monotime (https://github.com/pypa/pip/issues/1405).
+# Remove it (it's not a part of {opts}) to only install real releases.
+install_command = pip install {opts} {packages}
+
 [testenv:py26]
 basepython = python2.6
 deps = unittest2
@@ -89,9 +94,8 @@ commands = python -m tornado.test.runtests --ioloop=tornado.platform.twisted.Twi
 
 [testenv:py27-monotonic]
 basepython = python2.7
-# TODO: remove this url when the pypi page is updated.
 deps =
-     http://pypi.python.org/packages/source/M/Monotime/Monotime-1.0.tar.gz
+     Monotime
      futures
      mock
      pycurl