Secedgar

* Adds ``entry_filter`` property to ``secedgar.filings._index.IndexFilings`` to help filter out filings from day or quarter that aren't needed (thanks to reteps!)
* ``secedgar.filings.cik_lookup.CIKLookup`` tries to use ``secedgar.utils.cik_map.get_cik_map`` first when looking up tickers/company names (regardless of whether tickers are upper or lowercase)
* Adds validation to ``secedgar.utils.cik_map.get_cik_map`` to ensure correct key options are being used
* ``secedgar.client.network_client.NetworkClient`` now pauses at the end of request as well if `pause` is given.

Fixes bug where `DailyFilings` and `MasterFilings` does not use correct URLs when calling `save` method.

Fix `Filing` bug where filings do not work properly when `count` set to `None`.

* Fixes `DailyFilings` bug to properly fetch daily filings.
* Fixes `Filing` bug to fetch specified number of filings.

* `secedgar.filings.DailyFilings` added to allow easy access to every day's filings.
* `secedgar.utils.get_cik_map` added to add an easy and fast option for getting company CIKs.