#767 Improve Android Content download page

[Emmanuel Engelhart]

This is a feature request gathering many small improvements which should be done on http://www.kiwix.org/m/, a download page which is proposed to Android users to download contents.

The source code is available at:
https://sourceforge.net/p/kiwix/web/ci/master/tree/mobile-folder/

Here is the list of improvements:
-- Replace "Kiwix ZIM Contents" and "Content Downloads Filter" with only one title like "Download content for Kiwix"
-- Remove "Content Type" select box (we don't have enough content for now to justify such type of filtering)
-- "Language" selectbox should be automatically filled with the list of languages available at http://www.kiwix.org/wiki/Template:ZIMdumps (first column)
-- "Language" select box entry "Auto-detect" should be removed and autodetect should be applied at loading base on browser agent language
-- Replace "Download Link" label by "Download method"
-- Replace "Download link" select box by two radio buttons-- Remove "Filter button", each change on "Download method" or "Language" should automatically apply the filter and reload the results
-- Block the page during each loading of the result (modal dialog box) or darken the whole page
-- Make the filtering working for all languages, "Hindi" for example does not work.

[Emmanuel Engelhart]

This was successfuly done. Thank you Wilfredo.