gdal2tiles.py patch, updated readme, dockerfile

Dockerfile

@@ -14,4 +14,7 @@ WORKDIR "/var/www"
 RUN git clone https://github.com/pierotofy/node-OpenDroneMap .
 RUN npm install
 
+# Fix old version of gdal2tiles.py
+RUN (cd / && patch -p0) <patches/gdal2tiles.patch
+
 ENTRYPOINT ["/usr/bin/nodejs", "/var/www/index.js"]

README.md

@@ -42,7 +42,7 @@ If you are already running [OpenDroneMap](https://github.com/OpenDroneMap/OpenDr
 
 ```
 sudo curl --silent --location https://deb.nodesource.com/setup_6.x | sudo bash -
-sudo apt-get install -y nodejs
+sudo apt-get install -y nodejs python-gdal
 git clone https://github.com/pierotofy/node-OpenDroneMap
 cd node-OpenDroneMap
 npm install

patches/gdal2tiles.patch

@@ -0,0 +1,11 @@
+--- /usr/bin/gdal2tiles.py	2014-04-05 14:21:17.000000000 +0000
++++ gdal2tiles.py	2016-11-08 19:33:42.162188732 +0000
+@@ -783,7 +783,7 @@
+         self.out_srs = osr.SpatialReference()
+ 
+         if self.options.profile == 'mercator':
+-            self.out_srs.ImportFromEPSG(900913)
++            self.out_srs.ImportFromEPSG(3857)
+         elif self.options.profile == 'geodetic':
+             self.out_srs.ImportFromEPSG(4326)
+         else: