extended line item and cart feature to be able to calculate total from line items in the cart
integrated line item, cart and rental checkout form. still need to integrate payment
added profile pictures that was uploaded by user
user can now, remove line items from cart, and checkout. User can also delete cart
fixed cart. issue was when deleting user, current cart would not be destroyed. so when creating new user, previous cart would be displayed. its because the session id is used for cart id. fix was to do session cart_id to nil when destroying user
fixed user so that can not delete user if they have gear that is in some other users cart. also fixed so taht can't delete gear if that gear is in some other users cart
cleanup comments in several files
Merge branch 'cart_checkout' into develop

fixed cart, line items, users, and cleaned up comments
now user can't delete gear if another user has that gear in their account
also user can't delete their own account if they have gear that is another users cart
created dynamic search form. User can add condition fields and predicates dynamically. can choose attributes fields from gear and rental
Updated gear index to show 3 conditions: search by text, pickup date, and return date. Need to fixed date picker on the date fields.
fix nil:NilClass error when no input in search form from user. also implemented and/or query conditions using ransack
updated searchgear function to use squeel. index is still using ransack. need to find way to integrate ransack and squeel. squeel is beneficial becuase it allows us to write one code in ruby and this can be converted to sql for any database i.e. differences with sqlite and postgres. all searching should be done with teh searchpage view and searchpage function.