Enable port number directly type in and fix http request bug

[lawrencehj]

1. The port number up/down control was limited by minimum number of 8080, so when user directly type in the number, it would be corrected to 20000.
2. If user want to access a sensor with character like '{' or '}' in the id string, the web server can not reponse correcly.
   for example:
   http://127.0.0.1:8088/Sensor?action=Get&id=/nic/%7B3610E5A6-B1A2-46DE-ABCD-CA9D97BDE218%7D/throughput/7

[sergiye]

thanks for finding bugs, but нour version of fixes isn't entirely correct.

Simply removing the minimum in the port value isn't enough.

The sensor ID needs to be escaped in the request address itself (http://127.0.0.1:8088/Sensor?action=Get&id=/nic/%257B3610E5A6-B1A2-46DE-ABCD-CA9D97BDE218%257D/throughput/7).

But thanks to this, there's now error handling in the HTTP server, and the user will receive a 400 Bad Request error if the request is invalid.