pip install rucio fails with newer versions of pip
Apparently newer versions of pip don't like the three equals in the cx_oracle dependency. (Somewhere along the line internally it sticks parentheses around the version description, and then the parser chokes on that combination).

```
(rucio-test) [illingwo@fermicloud014 rucio-test]$ pip --version
pip 18.0 from /cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip (python 2.7)
(rucio-test) [illingwo@fermicloud014 rucio-test]$ pip install rucio
Collecting rucio
Exception:
Traceback (most recent call last):
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_internal/basecommand.py", line 141, in main
    status = self.run(options, args)
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_internal/commands/install.py", line 299, in run
    resolver.resolve(requirement_set)
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_internal/resolve.py", line 102, in resolve
    self._resolve_one(requirement_set, req)
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_internal/resolve.py", line 306, in _resolve_one
    set(req_to_install.extras) - set(dist.extras)
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2826, in extras
    return [dep for dep in self._dep_map if dep]
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2871, in _dep_map
    self.__dep_map = self._compute_dependencies()
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2881, in _compute_dependencies
    reqs.extend(parse_requirements(req))
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2942, in parse_requirements
    yield Requirement(line)
  File "/cloud/login/illingwo/rucio-test/lib/python2.7/site-packages/pip/_vendor/pkg_resources/__init__.py", line 2951, in __init__
    raise RequirementParseError(str(e))
RequirementParseError: Invalid requirement, parse error at "'(===6.3.'"
```


diff --git a/setup_rucio.py b/setup_rucio.py
index 078dfca94..ecd935df4 100644
--- a/setup_rucio.py
+++ b/setup_rucio.py
@@ -15,7 +15,7 @@
 # Authors:
 # - Mario Lassnig <mario.lassnig@cern.ch>, 2012-2014
 # - Vincent Garonne <vgaronne@gmail.com>, 2012-2018
-# - Martin Barisits <martin.barisits@cern.ch>, 2012-2017
+# - Martin Barisits <martin.barisits@cern.ch>, 2012-2018
 # - Wen Guan <wguan.icedew@gmail.com>, 2014
 # - Thomas Beermann <thomas.beermann@cern.ch>, 2014-2018
 
@@ -164,7 +164,7 @@ def write_requirements():
         req_file.close()
 
 
-oracle_extras = ['cx_oracle===6.3.1']
+oracle_extras = ['cx_oracle==6.3.1']
 postgresql_extras = ['psycopg2>=2.4.2']
 mysql_extras = ['PyMySQL']
 kerberos_extras = ['kerberos>=1.3.0', 'pykerberos>=1.2.1', 'requests-kerberos>=0.12.0']
['setup_rucio.py']