examples/http: support option parameters

examples/http: support option parameters

Now that webclient supports option parameters input.

* Webclient usage.
   . webclient GET http://127.0.0.1/ async=1
   . webclient PUT https://127.0.0.1/ async=1 entity=senddata

* Options
   . async=1          : Enable asynchronous mode (default is synchronous)
   . chunked=1        : Enable chunked encoding (default is disabled)
   . entity=DATA      : Input entity data (default is NULL)
   . test_entity=SIZE : Input test entity dummy data (default is 0)

Change-Id: I074a74507c72813621617731cd9215071cb7b461
Signed-off-by: Junyeon LEE <junyeon2.lee@samsung.com>