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/ehr/CMakeLists.txt

@@ -1,5 +1,5 @@
 upm_mixed_module_init (NAME ehr
-    DESCRIPTION "Ear-clip heart rate sensor"
+    DESCRIPTION "Ear-clip Heart Rate Sensor"
     CPP_HDR ehr.hpp
     CPP_SRC ehr.cxx
     REQUIRES mraa)

src/ehr/ehr.hpp

@@ -38,7 +38,7 @@ namespace upm {
   /**
    * @library ehr
    * @sensor ehr
-   * @comname  Ear-clip Heart Rate Sensor
+   * @comname Ear-clip Heart Rate Sensor
    * @type medical
    * @man seeed
    * @con gpio