Merge pull request #4 from shanegibbs/development

Saving and restoring variables
Merge pull request #5 from shanegibbs/development

Add operation
Merge pull request #6 from shanegibbs/development

Minus operator. Brackets around expressions.
Merge pull request #7 from shanegibbs/development

Integer multiple and divide
Add travis.yml
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Setting up travis-ci
Merge branch 'master' into development