Make esri url checks more general

[jacpete]

Purpose: Adapt esriUrl_isValid to accept valid, but non-service/feature URL's like the root of a server or a folder page like https://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics or https://sampleserver1.arcgisonline.com/ArcGIS/rest/services

Deprecated/Renamed Exported Functions:

• esriUrl_isValidID -> esriUrl_isValidFeature
• esriUrl_ServerUrl -> esriUrl_serviceUrl

Added Functions:

• esriUrl_isValidFolder
• esriUrl_isValidRoot
• esriUrl_isValidType (unexported but now does all the heavy lifting in the esriUrl_* functions)

Changed Functions:

• Output of esriUrl_parseUrl() used to be a list with the names: ["url", "scheme", "host", "instance", "restIndicator", "folderName", "serviceName", "layerID"] and is now a list with the names: ["url", "scheme", "host", "instance", "restIndicator", "folderPath", "serviceName", "serviceType", "featureID"]
• Added a token argument to most if not all public functions

[jacpete]

@elipousson Here is what I am pulling together to fix the esriUrl_isValid issues in #39 . I want to go a little deeper and make sure everything is still working correctly in some of the functions that don't have tests built for them yet. Main thing is a major update to generalize esriUrl_isValid, but I also made some slight changes in the output of esriUrl_parseUrl and changed a couple function names. The function names I changed I just did a simple wrapper around the original function with a deprecation warning. This will be what we use if we decide to change standardize function names in the package. Feel free to download the branch and play with it to see if it will work with your idea of the esriIndex function.