Failure to generate hotp with counter > 127

[chudel]

Hello,

Nice javascript. I receive an error when generating an hotp with a counter size > 127.

hotp.getOtp(secret,128) will fail: my console shows the following output:

URIError: malformed URI sequence
line 85 in Hotp.prototype.uintToString

[xikaos]

I'm also experiencing this issue.

[zyonse]

For anyone else with this issue, it's fixed in #5