doc: Scrubbed ALL sensor library descriptions

In an effort to clean-up and standardize UPM library
documentation, this commit updates (and in most cases,
unifies) the CMake description string AND CXX header
@comname string.

Strings were taken from datasheets when possible, spelling
mistakes were addressed, copy/paste errors where fixed,
Title Case was used, etc.

    * Tested/updated/added @web tags
    * Added/updated invalid sensor images
    * Added/updated @man tags, added missing manufacturers

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/si7005/CMakeLists.txt

@@ -1,5 +1,5 @@
 set (libname "si7005")
-set (libdescription "Digital I2C humidity and temperature sensor")
+set (libdescription "Digital I2C Humidity and Temperature Sensor")
 set (module_src ${libname}.cxx mraa-utils.cxx)
 set (module_hpp ${libname}.hpp)
 upm_module_init(mraa interfaces)

src/si7005/si7005.hpp

@@ -44,10 +44,11 @@ namespace upm {
 /**
  * @library si7005
  * @sensor si7005
- * @comname Silicon Labs Si7005 Humidity And Temperature Sensor
+ * @comname Digital I2C Humidity and Temperature Sensor
  * @altname Si7005
  * @type temp
  * @man silabs
+ * @web http://www.silabs.com/products/sensors/humidity-sensors/Pages/Si7005.aspx
  * @con i2c
  * @if itemperaturesensor
  *