Consider a more flexible "current environment" decision logic

[sgoings]

Right now we hold a link in ~/.rigger/vars to the vars file of the most recent rigger configure'd vars file.

This makes it a pain to deal with multiple cluster provision test etc. operations in parallel (such as in release testing).

Some options that have been discussed:

• keep this logic but also allow people to pass in a name for their cluster at configuration time as well as for all the commands

./rigger provision aws-1
./rigger test aws-2

• make the link smarter to just look in a directory structure within ~/.rigger/... that corresponds to the user's current working directory

[krancour]

make the link smarter to just look in a directory structure within ~/.rigger/... that corresponds to the user's current working directory

^ too much "magic," imo

I love the first option though.