Accept wildcards in the parser screen

All compatible Keys are passed on to the parser, for parsing in a combined
hex-key.  "Compatible" means all keys have the same number of columns and
the same style separators, and only 1 (optional) has a header.  Incompatible
sets complain in the parser GUI.
EC2 hdfs_config
Merge branch 'master' of github.com:0xdata/h2o