Improve Spring comparison in README (#2)

Update Gemfile.lock for version 0.2.0

Bump version to 0.2.0

Remove millisecond measurement from performance section

Remove User.group example from README

Match rails runner behavior - only output explicitly printed content

Fix hanging when server fails to start

Remove 'start' command - server auto-starts on first use

Remove 'help' command, keep only --help and -h flags

Change 'instant' to 'almost instant' for subsequent requests

Remove redundant note about global installation

Clarify that gem can be installed globally without modifying Gemfile

Add testing note to README Development section

Update TESTING.md with more nuanced explanation of integration test trade-offs

Add TESTING.md documentation