test: input etherscan API key through env

Merge pull request nanmu42#19 from nanmu42/develop

add desc param to ERC20Transfers()

Merge pull request nanmu42#12 from nanmu42/develop

Workaround for missing tokenDecimal for tokentx calls

minor API change: Field `TraceID` of struct `InternalTx` is now strin…

…g instead of int.

Fixed a bug on nil check, which could produce panic.

All users should update to this version.

v1.0.1 adds add Content-Type header when requesting

v1.0.0 First Step!