Reverted the setuptools dependency bump

CentOS 7 apparently still has a stone age setuptools version so the dependency can't be upgraded without breaking the ability of the package maintainers to create a native package. So an alternative method for providing the version information in the top level package's __init__ module was implemented.

Closes #130

apscheduler/__init__.py

@@ -1,6 +1,4 @@
 # These will be removed in APScheduler 4.0.
-parsed_version = __import__('pkg_resources').get_distribution('APScheduler').parsed_version
-version_info = tuple(int(x) if x.isdigit() else x for x in parsed_version.public.split('.'))
-version = parsed_version.base_version
-release = __version__ = parsed_version.public
-del parsed_version
+release = __import__('pkg_resources').get_distribution('APScheduler').version.split('-')[0]
+version_info = tuple(int(x) if x.isdigit() else x for x in release.split('.'))
+version = __version__ = '.'.join(str(x) for x in version_info[:3])

setup.py

@@ -37,7 +37,7 @@
         'setuptools_scm'
     ],
     install_requires=[
-        'setuptools >= 11',
+        'setuptools >= 0.7',
         'six >= 1.4.0',
         'pytz',
         'tzlocal >= 1.2',