Support global call

[turbo8p]

Problem

It would make the script way easier to use if it can run from anywhere.

Currently, the constraint is in the assume_role.sh which depends on setup.sh
This dependency make global script call impossible. I tried to symlink it and make it globally accessible like below

sudo ln -s /home/ec2-user/aws-sts-helper/assume-role.sh /usr/local/bin/assume_role
sudo ln -s /home/ec2-user/aws-sts-helper/get-session-token.sh /usr/local/bin/get_session_token

But when call the script assume_role, it complains that it cannot find setup.sh

[dacgray]

Should be able to do something like this: https://stackoverflow.com/questions/24112727/relative-paths-based-on-file-location-instead-of-current-working-directory

[dacgray]

Should be working for git bash in windows, and linux now.

Pls see readme for instructions.