replace some uses of str with repr
replace some uses of str with repr

Repr seems to make more sense when hashing (strives for unambiguity rather than readability) and also is faster on most primitive types.

pombredanne/lsh-hdc,pombredanne/lsh-hdc,escherba/lsh-hdc,escherba/lsh-hdc,pombredanne/lsh-hdc,escherba/lsh-hdc,pombredanne/lsh-hdc,escherba/lsh-hdc,escherba/lsh-hdc,pombredanne/lsh-hdc