Import shipments from CSV file and create temp table from permits

This pull request has a finished task (importing shipments) and a work in progress task (importing permits)

1. Importing shipments:

We have two types of shipments import:

   a) First time import

  There are some fixes to the original table that must be done in the beginning. To do this run:
  
  rake import:first_shipments path/to/file.csv

  Unfortunately the first csv is too big to store in github. Please ask me for it.


  b) Other imports

  Whenever you want to add new shipments to trade_shipments table you can run:
  
  rake import:first_shipments path/to/file.csv

2. Importing permits

  I am still working on this but it is already possible to run the following command to import permits to a temporary table called (permits_import)

  rake import:trade:permits