scrapers/eztv: Use regex instead of BeautifulSoup to get episodes list

BeautifulSoup is **too** slow in a raspberry pi and we are using very basic
things from it. So, as it was simple, this commit just replaces the uses of
BeautifulSoup to get season episodes using regex.

Also, the patch tries to be as simple as possible (to make more easy to catch
the mistakes). The "big" difference in the diff is that a whole BeautifulSoup
node was saved and then access using ".text" or ".href", and now we only save
the text (by using a regex group). So, in the diff lot of ".text" and ".href"
are removed.

Before this commit on my raspberry pi it took 45 seconds to get the episodes for
White Collar Season 5, and with this path it takes 10 seconds.
scrapers/eztv: Don't use BeautifulSoup to get show seasons either
scrapers/eztv: Don't use BeautifulSoup to get shows by letter
scrapers/eztv: Wait for show metadata only on idle

The metadata is needed for the loop. So there is no point in blocking for
"result()" when we still can go ahead and parse for the links.
Merge pull request #153 from rata/rpi

Improvements to eztv scraper on raspberrypi