PostFile now contains key parameter.

Key param is kind of dummy property, since PostFile is handled directly
by NanoHTTPD.fileUpload() method. The key parameter just signalizes
that key parameter is required for the call.
Merge branch 'master' of github.com:0xdata/h2o
Returns a JSON error if the client send unknown param.

The H2O rejects all REST request containing unknown parameters.
This behavior can be changed by passing argument:
  -check_rest_params false
Merge branch 'master' of github.com:0xdata/h2o
Merge branch 'master' of github.com:0xdata/h2o
Merge branch 'master' of github.com:0xdata/h2o