allow simulation in python sandbox
fix error message not displayed bug when no public test cases for mission
fix javascript bug for add test cases in mission
temporally removed is pending deletion default scope
update puma.sh, fix problem with fresh restart. and added memory footprint check
better log message for puma.sh
allow import of url lib
allow url lib (need refactor)
refactor mission action button rendering
update python sandbox to allow url lib
fix python csv file read
python allow generic arith package
better python open wrapper for handling other optional arguments
migration to add missing indexes
updated schema
Merge branch 'master' of github.com:Coursemology/coursemology.org into dev/raymoond_dev
image upload process bar: clean process upon dismiss of modal
add index on activity create_at column
Merge branch 'master' of github.com:Coursemology/coursemology.org into dev/raymoond_dev

Conflicts:
	app/assets/javascripts/image_uploader.js
Merge branch 'master' of github.com:Coursemology/coursemology.org into dev/raymoond_dev