write_yml: Write config.yml file for cloudml_train
In tianwei-zhang/easyAI: Democratize AI

Write config.yml file for cloudml_train

1 2	write_yml(num_layer, max_units, start_unit, max_dropout, min_dropout, max_lr, min_lr, machine_type)

`num_layer`	Number of hidden layer_dense
`max_units`	the maximum number of hidden units in a layer. Default to an optimized value based on data
`start_unit`	the minimum number of hiddent units in a layer. Default to 5
`max_dropout`	A number between 0 and 1 indicating the maximum dropoff rate in a layer. Default to 0.2
`min_dropout`	A number between 0 and 1 indicating the minimum dropoff rate in a layer. Default to 0
`max_lr`	maximum learning rate in a run. Default to 0.2
`min_lr`	minimum learning rate in a run. Default to 0.001
`machine_type`	type of server to use. Could be standard, standard_gpu, standard_p100. For more visit https://cloud.google.com/ml-engine/docs/training-overview#machine_type_table