Add Find functions with filter parameter

[jovandeginste]

This allows to find any resource of a given type, filtered by some attributes.

Eg:

filter := map[string]string{
    "ipv46": "10.71.136.50",
}
result, err := client.FindFilteredResourceArray("csvserver", filter)

[jovandeginste]

@chiradeep I can take a look!

[chiradeep]

@jovandeginste thanks. I already wrote a test.