ENH: Reorganized module to allow for future growth

Reorganized the arch code to reside in univariate rather than in the root
Imported core routines in the arch module
Added temporary compatibility fixes with deprecation warnings
Merge pull request #5 from hugle/fcast_dev

Add required packages in setup file
Merge pull request #6 from bashtage/reorganize-univariate

ENH: Reorganized module to allow for future growth