ibovespa(ibov) is the largest index in Brazil's stocks exchange.
The br_index folder has support for downloading new companies for the current index composition.
And has support, as well, for downloading companies from historic composition of ibov index.

Partially resolves issue #956

…'s stocks exchange (B3)

Together with commit c2f933 it resolves issue #956

…t file

…BOVIndex

…bov index

…ode usability.

Message in the PR request to understand the context of the change

In the course of reviewing this PR we found two issues.

    1. there are multiple places where the get_instruments() method is used,
	and we feel that scripts.index.py is the best place for the
	get_instruments() method to go.
    2. data_collector.utils has some very generic stuff put inside it.

The reason to use retry=2 is due to the fact that
Yahoo Finance unfortunately does not keep track of the majority
of Brazilian stocks.

Therefore, the decorator deco_retry with retry argument
set to 5 will keep trying to get the stock data 5 times,
which makes the code to download Brazilians stocks very slow.

In future, this may change, but for now
I suggest to leave retry argument to 1 or 2 in
order to improve download speed.

In order to achieve this code logic an argument called retry_config
was added into YahooCollectorBR1d and YahooCollectorBR1min

Using partial as `fire.Fire(partial(get_instruments, market_index="br_index" ))`
will make the interface easier for the user to execute the script.
Then all the collector.py CLI in each folder can remove a redundant arguments.

This way we don't have to use hasattr to access the retry attribute as previously done