Add check for mod_php before setting php_value for upload size

This will prevent errors on systems that don't allow overriding the php
values from within the .htaccess files. This will only check for php 7+
though, as the mod_php directive is version specific. This is okay for
now, as we officially only support PHP 7.1+

public/.htaccess

@@ -1,9 +1,6 @@
 # Comment this line if you are getting: "Option SymLinksIfOwnerMatch not allowed here" error in Apache
 Options +SymLinksIfOwnerMatch
 
-php_value upload_max_filesize 50M
-php_value post_max_size 100M
-
 # php5_module automatically handles HTTP_AUTHORIZATION headers, but fcgi_module does not.
 <IfModule mod_setenvif.c>
     <IfModule mod_proxy_fcgi.c>
@@ -12,7 +9,6 @@ php_value post_max_size 100M
 </IfModule>
 
 <ifModule mod_rewrite.c>
-
     RewriteEngine On
 
     # Map all admin endpoints to the admin app (except static files)
@@ -22,5 +18,9 @@ php_value post_max_size 100M
     # Map all other requests to invoke the API router (except static files)
     RewriteCond %{REQUEST_FILENAME} !-f
     RewriteRule !^admin index.php?%{QUERY_STRING} [L]
-
 </ifModule>
+
+<IfModule mod_php7.c>
+  php_value upload_max_filesize 50M
+  php_value post_max_size 100M
+</IfModule>