fix Makefile chmod (644)
replace MD5SUM with HASH
add PKG_MIRROR_HASH when PKG_SOURCE_PROTO:=git

(PKG_SOURCE_PROTO:=svn tarballs are not reproducible for now)

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

Update several dependencies, as well:

* django-compressor -> 2.1.1
* django-constance -> 1.3.4
* django-restframework -> 3.5.4
* django-statici18n -> 1.3.0
* django -> 1.8.17
* openpyxl -> 2.4.2
* python-dateutil -> 2.6.0
* python-urllib3 -> 1.20

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Solves "bash: easy_install: command not found" error during build

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Avoids source filename conflicts and the need to delete source packages
at the end of the prepare stage. This has forced the buildenv to rebuild
the packages even if they were built already.

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>

Signed-off-by: Gergely Kiss <mail.gery@gmail.com>
Tested-by: Gergely Kiss <mail.gery@gmail.com>