update build scripts and examples, add helper script (#9)

* update build scripts and examples, add helper script

* have Read-SoilIsDry return a bool

* add full demo script

Author: TylerLeonhardt

Examples/BME280/Microsoft.PowerShell.IoT.BME280.psd1

@@ -0,0 +1,15 @@
+@{
+    GUID="eb74e8da-9ae2-482a-a648-e96550fb8739"
+    Author="Microsoft Corporation"
+    CompanyName="Microsoft Corporation"
+    Copyright="© Microsoft Corporation. All rights reserved."
+    Description='PowerShell module for working with Bosch Sensortec BME280 sensor.'
+    ModuleVersion="1.0.0.0"
+    PowerShellVersion="3.0"
+    FunctionsToExport = @('Get-BME280ChipID','Get-BME280Data','Get-BME280Device')
+    DotNetFrameworkVersion = 4.5
+    CmdletsToExport = '*'
+    AliasesToExport = @()
+    NestedModules=@('PSIoT','Microsoft.PowerShell.IoT.BME280.psm1')
+    HelpInfoURI = 'https://go.microsoft.com/fwlink/?LinkId=393254'
+}