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/mpl3115a2/CMakeLists.txt

@@ -1,5 +1,5 @@
 set (libname "mpl3115a2")
-set (libdescription "Pressure/Temperature Sensor")
+set (libdescription "I2C Precision Altimeter")
 set (module_src ${libname}.cpp)
 set (module_hpp ${libname}.hpp)
 upm_module_init(mraa)

src/mpl3115a2/mpl3115a2.hpp

@@ -63,7 +63,7 @@ namespace upm {
 /**
  * @library mpl3115a2
  * @sensor mpl3115a2
- * @comname MPL3115A2 Atmospheric Pressure Sensor
+ * @comname I2C Precision Altimeter
  * @type pressure
  * @man freescale
  * @web http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MPL3115A2