Fix captcha codes about esaj

[clente]

Refactoring of CPOPG-TJAM/BA/SC (hopefully) finished with de83dc0. Waiting validation by @jtrecenti before moving on to CPOSG-TJSC, DJE, and parsers.

[jtrecenti]

We need to check the captcha version of each site. The old one is one image containing 5 characters. The second is a json file containing an image with many (variable) letters and the color to consider.

[clente]

But was my implementation of baixar_tj**() correct? baixar_tjam() and baixar_tjsc() are in the new style, while baixar_tjba() is in the old.

If I implemented these 3 correctly, I'll go on to implementing the functions for the other TJs.

P.S.: Would it be interesting to have a general baixar() function? Its argument would be the abbreviation of a state and it would call the corresponding baixar_tj**() method.

[jtrecenti]

I think we need to rewrite the API. What do you think it is more efficient: Rewrite existing functions and clean the code or implement all TJ's and then modify the API?