Added "Agile Android Software Development" eBook

Added "Agile Android Software Development" eBook in the list under the Android section.  The book is currently in writing progress, but new chapters are released as soon they are copy-edited.  "Release 1.0" is expected in January 2015.

free-programming-books.md

@@ -598,6 +598,7 @@
 * [Alef Language Reference Manual](http://doc.cat-v.org/plan_9/2nd_edition/papers/alef/ref)
 
 ### Android
+* [Agile Android Software Development](http://www.agiledroid.com) (PDF, epub, mobi - need email confirmation) by Etienne Savard
 * [Android 4 App Development Essentials](http://www.techotopia.com/index.php/Android_4_App_Development_Essentials)
 * [Android Programming Guide for Beginners](http://eduonix.com/offers/Android_ebook_free_offer.html) (PDF - need email confirmation)
 * [Android Programming Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/android) ([PDF](https://www.syncfusion.com/content/downloads/ebook/Android_Programming_Succinctly.pdf), [Kindle](https://www.syncfusion.com/content/downloads/ebook/Android_Programming_Succinctly.mobi)) *(Just fill the fields with any values)*