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/o2/CMakeLists.txt

@@ -1,5 +1,5 @@
 upm_mixed_module_init (NAME o2
-    DESCRIPTION "Oxygen (O2) concentration sensor"
+    DESCRIPTION "Oxygen (O2) Concentration Sensor"
     C_HDR o2.h
     C_SRC o2.c
     CPP_HDR o2.hpp

src/o2/o2.hpp

@@ -36,11 +36,12 @@ namespace upm {
   /**
    * @library o2
    * @sensor o2
-   * @comname O2 Sensor
+   * @comname Oxygen (O2) Concentration Sensor
    * @altname Grove O2 Sensor
    * @type gaseous
    * @man seeed
    * @con analog
+   * @web http://wiki.seeed.cc/Grove-Gas_Sensor-O2/
    *
    * @brief API for the Grove O2 Oxygen Gas Sensor
    *