initial commit for the pdf report generation repository

the task i've completed so far are:
. designed the DB for stocks actions taking into account the data integrity (primary keys, foreign keys, table constraints, etc.) and the compatibility with other DBMSs (MySQL, SQLite, etc.)

. generated all the .sql scripts for the DB's DDL (Data Definition Language) (creation of tables, populating tables, etc.).

. generated all the .rb scripts for the DB's DDL (a ruby 'interface' for maintenance tasks).
added the note related with the owner (client) whose actions are being sold or bought in the .csv or .xlsx files
implemented the 'crawlers' hierarchy and added a lightweight django website to test the web crawler

some details should be noted:
. the django website is some sort of 'phony yahoo finance' service in order to test the web crawler
. only some preliminary test on the crawlers were made.
. the implementation is open to extension. we can add a 'crawler' that behaves the way we want because the implementation only takes care of the general aspects of a crawler.
. i recommend that some threads should be added to the crawler implementation, specially if we're dealing with remote resources.
implemented the 'stock readers' hierarchy

some details should be noted:
. only some preliminary test on the stock readers were made.
. the implementation is open to extension. we can add a 'stock reader' for other kind of data because the implementation only takes care of the general aspects of a stock reader.
implemented the 'data_providers' hierarchy and performed a 1st cicle of code refactoring

some details should be noted:
. only some preliminary test on the data providers were made.
. the implementation is open to extension. we can add a new 'data provider' that behaves the way we want because the implementation only takes care of the general aspects of a 'data provider'.
merging work at home with the github repository