Support lowercase hex char

[inkeliz]

Searching for a block using lowercase will return a error, "Unknown Block". I think the explorer must support lower and upper case letters.

Let's supose a block C4F62B30D530765229A44F7515E447FB9B7435CB76832291A488F950B4BDF3F2,
Using the lower-case: https://nanocrawler.cc/explorer/block/c4f62b30d530765229a44f7515e447fb9b7435cb76832291a488f950b4bdf3f2

Useing the upper-case:
https://nanocrawler.cc/explorer/block/C4F62B30D530765229A44F7515E447FB9B7435CB76832291A488F950B4BDF3F2

The "Search" button didn't work using lowercase char, either.