Electron desktop client added

Electron Client/node_modules/nugget/usage.txt

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+Usage: nugget <urls> [options]
+  -o         output filename
+  -d         output parent directory
+  -c         resume aborted download
+  -f         ignore response codes > 299
+  -s         concurrent socket limit (default infinity)
+  -q         disable logging
+  --stdin    download all urls written to stdin (newline delimited)