Fix #39 incorrect handling of bytesX arguments in solidityPack()

[mjmau]

Before this fix:

abi.solidityPack(
    [ 'bytes32', 'uint32', 'uint32', 'uint32', 'uint32' ],
    [ new Buffer('123456', 'hex'), 6, 7, 8, 9 ]
)
=> 1234560000000000000000000000000000000000000000000000000000000000

After this fix:

abi.solidityPack(
    [ 'bytes32', 'uint32', 'uint32', 'uint32', 'uint32' ],
    [ new Buffer('123456', 'hex'), 6, 7, 8, 9 ]
)
=> 123456000000000000000000000000000000000000000000000000000000000000000006000000070000000800000009

[coveralls]

Coverage remained the same at 83.18% when pulling bff8a2b on MichaelMaurer:mjm-solidity-pack-bytes32 into 4a33f23 on ethereumjs:master.

[axic]

Thank your for the fix!