Removed Subversion section, and added need for npm

Out of the box, installation needs running npm install too. Subversion instructions removed by indication of @thijskh

docs/simplesamlphp-install-repo.md

@@ -38,21 +38,8 @@ Ask git to update to the latest version:
     git fetch origin
     git pull origin master
 
-Install or upgrade the external dependencies with Composer ([get composer](http://getcomposer.org/)):
+Install or upgrade the external dependencies with Composer and npm ([get composer](http://getcomposer.org/)):
 
     php composer.phar install
+    npm install
 
-
-Migrating from Subversion
--------------------------
-
-If you installed SimpleSAMLphp from subversion, and want to keep updated on the development, you will have to migrate
-your installation to git. First, follow the steps to get a fresh install from github in a different directory. Skip the
-steps regarding configuration and metadata initialization, and copy all the files you might have modified instead (not
-only configuration and metadata, but also any custom modules or templates). Finally, proceed to install Composer and
-install all the dependencies with it. You may want to add all your custom files to the '.gitignore' file.
-
-If you really want to use subversion instead of git, or it is impossible for you to migrate (you cannot install git, for
-example), you might want to do a fresh install like the one described here, but using github's subversion interface.
-Refer to [github's documentation](https://help.github.com/articles/support-for-subversion-clients) for detailed
-instructions on how to do that.