Raise exception when cannot find configuration.

Fixes #1645.
Cleaned up unused imports
Handling site and custom configs differently by returning default empty configs
Ignoring missing custom and site configs.
Updated changelog
Merge pull request #1646 from rhyolight/config-runtime-exception

Raise exception when cannot find configuration.
Setting pip version on upgrade for travis
Assuming Travis has pip==1.5.X installed
Updates nupic.core to a66466edf8def8eac0a85c3ab7526195bc6918ed.
Merge pull request #1651 from numenta-ci/core-update-sha

Updates nupic.core to latest built SHA.
Removed check for local config file...

Which was happening outside of pkg_resources
Merge pull request #1653 from rhyolight/config-bugfix

Removed check for local config file...
Release 0.0.7
Continuing development on 0.0.8-dev
Stable development status classifier for pypi
Release 0.0.8
Continuing development on 0.0.9-dev
Distributing  files from  in binary packages.
Hard-coding version string
Release 0.0.9