Added files from previous PR
Added separate method to Vector
Merge branch 'master' of https://github.com/sympy/sympy into newfunctions
Fixed travis errors
Merge branch 'master' of https://github.com/sympy/sympy into newfunctions
Added raises test to test_scalar_potential
Merge pull request #2922 from srjoglekar246/newfunctions

Basic field functions for sympy.physics.vector