Update GitHub owner for webpage links.

That is, burnman-project->geodynamics, for GitHub links.
fix citation on homepage
add a link to geodynamics.org
Merge pull request #48 from tjhei/homepage-links

Update homepage
Manual Copy Editting

Fixed citations, added units to classes that were missing
Fixed T in isothermal bulk modulus

See title
Fixed comment on Z

Formula unit
Typo

Typo
Merge pull request #49 from lordkman/Cay_man

Manual Copy Editting
Added new VRH and HS bound benchmarks
Edited comments
Removed lovely unsquashable umlaut
Merge pull request #50 from bobmyhill/velocity_averaging

Velocity averaging
automating setting of the equation of state
fix examples