Update free-programming-books-gr.md
add two japanese books
Merge pull request #1133 from luminousspice/ja

[ja] Added Swift book
Merge pull request #1134 from raven38/ja

add two japanese books
added two new Perl resources in Chinese
Merge pull request #1135 from sunxb10/master

added two new Perl resources in Chinese
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.
Merge pull request #1136 from Symbiosoft/master

Added "Agile Android Software Development" eBook
added to index as requested
Merge pull request #1138 from borgified/patch-2

Patch 2
added "The Design and Implementation of the Anykernel and Rump Kernels"
Merge pull request #1140 from ligurio/master

added "The Design and Implementation of the Anykernel and Rump Kernels"
[ja] Added ruby for iOS book