[Breaking] Change all time input parameters to milliseconds. (#78)

Changes all functions that accept a time parameter to use milliseconds instead of seconds.

* Adds duration input to NimBLEDevice::startAdvertising and NimBLEServer::startAdvertising.

docs/Migration_guide.md

@@ -17,6 +17,7 @@ For more information on the improvements and additions please refer to the [clas
     * [Remote Services](#remote-services)
     * [Remote characteristics](#remote-characteristics)
     * [Security](#client-security)
+* [Scanning](#scan-api)
 * [General Security](#security-api)
 * [Configuration](#arduino-configuration)
 <br/>
@@ -321,6 +322,11 @@ The client will automatically initiate security when the peripheral responds tha
 The default configuration will use "just-works" pairing with no bonding, if you wish to enable bonding see below.
 <br/>
 
+<a name="scan-api"></a>
+### BLE Scan
+The scan API is mostly unchanged from the original except for `NimBLEScan::start`, in which the duration parameter is now in milliseconds instead of seconds.
+<br/>
+
 <a name="security-api"></a>
 ## Security API
 Security operations have been moved to `BLEDevice` (`NimBLEDevice`).

docs/New_user_guide.md

@@ -146,7 +146,7 @@ After initializing the NimBLE stack we create a scan instance by calling `NimBLE
 
 Once we have created the scan we can start looking for advertising servers.  
 
-To do this we call `NimBLEScan::start(duration)`, the duration parameter is a uint32_t that specifies the number of seconds to scan for,  
+To do this we call `NimBLEScan::start(duration)`, the duration parameter is a uint32_t that specifies the number of milliseconds to scan for,  
 passing 0 will scan forever.  
 
 In this example we will scan for 10 seconds. This is a blocking function (a non blocking overload is also available).  
@@ -162,7 +162,7 @@ void app_main(void)
     NimBLEDevice::init("");
     
     NimBLEScan *pScan = NimBLEDevice::getScan();
-    NimBLEScanResults results = pScan->start(10);
+    NimBLEScanResults results = pScan->start(10 * 1000);
 }
 ```
 <br/>
@@ -302,7 +302,7 @@ void app_main(void)
     NimBLEDevice::init("");
     
     NimBLEScan *pScan = NimBLEDevice::getScan();
-    NimBLEScanResults results = pScan->start(10);
+    NimBLEScanResults results = pScan->start(10 * 1000);
     
     NimBLEUUID serviceUuid("ABCD");