Merge pull request #8 from jules27/release

Release
Remove the why page.
Add a model and create migration for styles.
Rename products db table to parts. Add parts to seed file.
Rename code from products to parts. Correct pricing for parts in seed file. Update orders table.
Preorder page: add HTML and CSS for selecting style.
Create OrdersParts model and db migration. Modify some existing db schemas to enforce non-null.
Change database use from sqlite to postgres.
Stop git from tracking database.yml and add it to git ignore file.
Merge pull request #9 from jules27/preorder

Preorder
Add logic and styling to preorder page. Make cover style selection work.
Preorder page: add doors and windows, and table of parts. Add styling for changing quantity for each part. Page still needs work to be completely functional.
Move some inline styles to stylesheet. Start making changes to price table totals.
Preorder page: + and - updates total price now
Wrap up javascript for preorder page: quantity increment and decrement will update the grand total correctly.
Preorder page: Correct local variables in js file. Add function to adjust total price in each part's row. Refactor code so that both the parts total and the grand total use the same function but with different selectors.
Add setting values and constants for parts' max quantity. Add css adjustments in js file to keep alignment of + and - buttons even when the quantity changes.
Make more changes to preorder page: add window and door sliders, change +/- images.
Enforce a minimum of 1 for base stations.
Remove unused + and - blue buttons.