Cleanup for spring.io, update docs

This commit contains a number of changes, no functional difference in
the app but a general cleanup of look and docs:

- removed the Gemfile which is now redundant, Cloud Foundry CLI is no
longer a Ruby app
- updated various parts of the README to reflect changes to Spring Boot
CLI (local flag no longer exists, etc) and new CF deployment procedure.
- fixed references to www.springsource.com -> spring.io throughout web
content
- added favicon reflecting new Spring branding
- updated github URLs springsource -> spring-projects

static/install.sh

@@ -50,7 +50,7 @@ To get started:
   $ spring --version
   $ spring help
 
-And take a look at the README at https://github.com/springsource/spring-boot#readme.
+And take a look at the README at https://github.com/spring-projects/spring-boot#readme.
 
 EOF
 elif type sudo >/dev/null 2>&1; then
@@ -64,7 +64,7 @@ To get started:
   $ spring --version
   $ spring help
 
-And take a look at the README at https://github.com/springsource/spring-boot#readme.
+And take a look at the README at https://github.com/spring-projects/spring-boot#readme.
 
 EOF
     else
@@ -76,7 +76,7 @@ Couldn't create the symlink. Please either:
   (3) Rerun this command to try again.
 
 Then to get started, take a look at 'spring help' or see the README at
-https://github.com/springsource/spring-boot#readme.
+https://github.com/spring-projects/spring-boot#readme.
 EOF
     fi
 else
@@ -89,8 +89,8 @@ Now you need to do one of the following:
         cp ${SPRING_HOME}/bin /usr/bin/spring
 
 Then to get started, take a look at 'spring help' or see the README at
-https://github.com/springsource/spring-boot#readme.
+https://github.com/spring-projects/spring-boot#readme.
 EOF
 fi
 
-trap - EXIT
+trap - EXIT