Create and use getNamedMapProvider middleware

yarn.lock

@@ -2,7 +2,7 @@
 # yarn lockfile v1
 
 
-"abaculus@github:cartodb/abaculus#2.0.3-cdb1":
+abaculus@cartodb/abaculus#2.0.3-cdb1:
   version "2.0.3-cdb1"
   resolved "https://codeload.github.com/cartodb/abaculus/tar.gz/f5f34e1c80cdd8d49edd1d6fe3b2220ab2e23aaf"
   dependencies:
@@ -226,7 +226,7 @@ camshaft@0.60.0:
     dot "^1.0.3"
     request "^2.69.0"
 
-"canvas@github:cartodb/node-canvas#1.6.2-cdb2":
+canvas@cartodb/node-canvas#1.6.2-cdb2:
   version "1.6.2-cdb2"
   resolved "https://codeload.github.com/cartodb/node-canvas/tar.gz/8acf04557005c633f9e68524488a2657c04f3766"
   dependencies:
@@ -252,7 +252,7 @@ carto@CartoDB/carto#0.15.1-cdb1:
     optimist "~0.6.0"
     underscore "~1.6.0"
 
-"carto@github:cartodb/carto#0.15.1-cdb3":
+carto@cartodb/carto#0.15.1-cdb3:
   version "0.15.1-cdb3"
   resolved "https://codeload.github.com/cartodb/carto/tar.gz/945f5efb74fd1af1f5e1f69f409f9567f94fb5a7"
   dependencies:
@@ -2223,7 +2223,7 @@ through@2:
   version "2.3.8"
   resolved "https://registry.yarnpkg.com/through/-/through-2.3.8.tgz#0dd4c9ffaabc357960b1b724115d7e0e86a2e1f5"
 
-"tilelive-bridge@github:cartodb/tilelive-bridge#2.3.1-cdb4":
+tilelive-bridge@cartodb/tilelive-bridge#2.3.1-cdb4:
   version "2.3.1-cdb4"
   resolved "https://codeload.github.com/cartodb/tilelive-bridge/tar.gz/faa2b638da2d119b78281575d40255cb523f6ca6"
   dependencies:
@@ -2231,7 +2231,7 @@ through@2:
     mapnik-pool "~0.1.3"
     sphericalmercator "1.0.x"
 
-"tilelive-mapnik@github:cartodb/tilelive-mapnik#0.6.18-cdb3":
+tilelive-mapnik@cartodb/tilelive-mapnik#0.6.18-cdb3:
   version "0.6.18-cdb3"
   resolved "https://codeload.github.com/cartodb/tilelive-mapnik/tar.gz/23bd1c31dd57d0b76c86b9f1eaf62462b3c17d01"
   dependencies: