Nouveau helper ynh_webpath_available et ynh_webpath_register (#235)

* Nouveau helper ynh_path_validity
Simplement un wrapper de yunohost app checkurl.
Peut-être une occasion de lui donner un autre nom plus parlant.
Il me semble justement qu'il en était question.
Conflicts:
	data/helpers.d/network
* Renaming ynh_path_validity to ynh_webpath_available
* Splitting domain and path
* Use the new url-available command instead of deprecated checkurl
* Adding ynh_webpath_register
* [enh] Check before register
- Need to be tested.
- And... probably lack a echo to inform in case of error.
* Fixing helper following discussion with Maniack

data/helpers.d/network

@@ -36,4 +36,32 @@ ynh_find_port () {
 		port=$((port+1))	# Else, pass to next port
 	done
 	echo $port
-}
+}
+
+# Check availability of a web path
+#
+# example: ynh_webpath_available some.domain.tld /coffee
+#
+# usage: ynh_webpath_available domain path
+# | arg: domain - the domain/host of the url
+# | arg: path - the web path to check the availability of
+ynh_webpath_available () {
+	local domain=$1
+	local path=$2
+	sudo yunohost domain url-available $domain $path
+}
+
+# Register/book a web path for an app
+#
+# example: ynh_webpath_register wordpress some.domain.tld /coffee
+#
+# usage: ynh_webpath_register app domain path
+# | arg: app - the app for which the domain should be registered
+# | arg: domain - the domain/host of the web path
+# | arg: path - the web path to be registered
+ynh_webpath_register () {
+	local app=$1
+	local domain=$2
+	local path=$3
+	sudo yunohost app register-url $app $domain $path
+}