Add ApproxFunBase and specialfunction tests (#283)

Author: jishnub

src/specialfunctions.jl

@@ -18,7 +18,7 @@ end
 ^(f::Fun{Jacobi},k::Integer) = intpow(f,k)
 ^(f::Fun{Jacobi},k::Real) = Fun(f,Chebyshev)^k
 
-
+log(f::Fun{<:PolynomialSpace{<:ChebyshevInterval}}) = invoke(log, Tuple{Fun}, f)
 function log(f::Fun{<:PolynomialSpace{<:IntervalOrSegment}})
     g = log(setdomain(f, ChebyshevInterval()))
     setdomain(g, domain(f))