SymPy: sha1 bump

remove render call from plot
Clang.jl: bump sha1
Merge pull request #254 from ihnorton/patch-3

Bump clang.jl sha1
Bump Units sha1 (literal string breakage fix)
New Cairo version (update to Base.Graphics, various enhancements)
New Tk version (update for Base.Graphics, many improvements)
New Images version (move display to ImageView, many improvements)
Bump FactCheck sha1
Merge pull request #255 from zachallaun/FactCheck

Bump FactCheck sha1
Bump FunctionalCollections sha1
Merge pull request #256 from zachallaun/FunctionalCollections

Bump FunctionalCollections sha1
Bump Tk sha1 (convenience methods, move visibility into Window constructor)
Bump Cairo sha1 (coordinate convenience wrappers)
Bump MAT sha1
Bump StrPack sha1
Add Memoize.jl, an improved version of extras/memoize.jl
Add DataFrames v0.2.3
Added LibExpat
Merge pull request #257 from amitmurthy/LibExpat

Added LibExpat