Merge get-macaroon, view-token and other scripts into dCacheScripts

[onnozweers]

We want to rename SpiderScripts to dCacheScripts, see #118.

After that, we can move a few dCache client scripts from GridScripts into dCacheScripts. The main reason is that some code is (almost) duplicated. Also, these tools are not ojnly for Grid users. Also, ada and get-macaroon are often used together. Makes sense to bundle them into one toolkit.

[onnozweers]

In GridScripts there are also some things that don't need to be merged into dCacheScripts. For example: docker-ui. That's a tool to build a container with the Grid user interface tools. It's not specifically meant for dCache. Similar for voms and ey.