Explicity #close each zip member file that has been opened via #fopen.

Updated example to also include explicit #close on #fopen'ed files.

Moved to more efficient block format on fopen.
Removed unneeded Digest::MD5 require.
Changed do/end style block to brace style around #fopen calls.
Merge pull request #9 from xunker/use_block_with_fopen_read

Explicity #close each zip member file that has been opened via #fopen.