Do not pass tile grid to getTile and tileUrlFunc

getTile and the tileUrlFunc are functions of the source, so they do need to be passed the tile grid. The tile source knows its tile grid, and can get the projection's tile grid if it doesn't have a tile grid.
Download Plovr into build directory

This means that all build artefacts except for the examples are in
build.
Add logging messages to indicate when a download is in progress
Add logging messages for downloading proj4js
Merge pull request #454 from twpayne/download-plovr-into-build-dir

Download plovr into build dir
Merge pull request #450 from elemoine/projection-null

Do not pass tile grid to getTile and tileUrlFunc
Update to latest version of pake
Merge pull request #455 from twpayne/update-pake

Update to latest version of pake
Hide the zoom buttons on print
Remove unused ol-renderer-webgl-canvas css class
Merge pull request #440 from fredj/css-print

css cleanups
Merge branch 'master' into cesium
Use new getTile signature