Revert "Rename Alert to DependencyAlert"

This reverts commit 2dca5362bffad2510f5939e92c5ec33b341a1950.
Cleanup README
rename PROJECT_SLUG to GEMNASIUM_PROJECT_SLUG

closes #10
Rename API_KEY to GEMNASIUM_TOKEN

closes #4
rename API_ENDPONT to GEMNASIUM_API_ENDPOINT
Don't panic if project slug is empty

close #5
Minor fixes and prepare for 0.2.1