Test net-imap with ruby/net-imap#593

Delete test/net/imap/test_data_lite.rb, because the target of this
test file has been deleted by [ruby/net-imap#543].

[ruby/net-imap#543]: ruby/net-imap#593

Author: nobu

gems/bundled_gems

@@ -13,7 +13,7 @@ test-unit           3.7.7   https://github.com/test-unit/test-unit
 rexml               3.4.4   https://github.com/ruby/rexml
 rss                 0.3.2   https://github.com/ruby/rss
 net-ftp             0.3.9   https://github.com/ruby/net-ftp
-net-imap            0.6.2   https://github.com/ruby/net-imap
+net-imap            0.6.2   https://github.com/ruby/net-imap            d9ae35ef913a45f83387b8444cdce4fb1cbf01af
 net-pop             0.1.2   https://github.com/ruby/net-pop
 net-smtp            0.5.1   https://github.com/ruby/net-smtp
 matrix              0.4.3   https://github.com/ruby/matrix