Merge remote-tracking branch 'pr/237' into develop

Twitter Feature on Main-View from @loadtocode

Twitter feature within home/index of LEAP web app as feed of tweets of one user's twitter account

How to use it: set up an Application-only authentication by twitter (https://dev.twitter.com/oauth/application-only) and then create a config/secrets.yml including:
```
development:
  twitter:
    enabled: false # set to true for usage
    twitter_handle: XXXXX #put your twitter handle here
    bearer_token: XXXXX #put your bearer token here
test:
  twitter:
    enabled: false # set to true for usage
    twitter_handle: XXXXX #put your twitter handle here
    bearer_token: XXXXX #put your bearer token here
```

things in the PR:

- [x] gemfile:twitter
- [x] twitter helper (caching (to avoid reaching twitter rate limits)
- [x] index twitter view
- [x] twitter css (twitter design as discussed in call: Profil-Header: Picture, Link to twitter + twitter_handle; removed picture and twitter_handle from individual tweet, heading aligns at the top, only the last 3 tweets are shown)
- [x] script to generate bearer token
- [x] script to invalidate generated bearer token
- [x] documentation (Readme + Doc)

2 files changed, 73 insertions, 0 deletions

diff --git a/app/assets/stylesheets/application.scss b/app/assets/stylesheets/application.scss
index 856a559..f42044b 100644
--- a/app/assets/stylesheets/application.scss
+++ b/app/assets/stylesheets/application.scss
@@ -16,6 +16,7 @@
 // LEAP web app specific overrides
 //
 @import "leap";
+@import "twitter";
 
 // And finally bootswatch style itself
 // @import "bootswatch/cerulean/bootswatch";
diff --git a/app/assets/stylesheets/twitter.scss b/app/assets/stylesheets/twitter.scss
new file mode 100644
index 0000000..b2233d0
--- /dev/null
+++ b/app/assets/stylesheets/twitter.scss
@@ -0,0 +1,72 @@
+.twitter {
+  position: relative;
+}
+
+.twitter_header {
+  font-size: 16px;
+  text-align: left;
+  margin-bottom: 55px;
+  padding: 10px 8px;
+}
+
+.twitter_id {
+  position: absolute;
+}
+
+.twitter_image_frame {
+  display: block;
+  width: 40px;
+  height: 40px;
+  overflow: hidden;
+  position: absolute;
+  left: 0;
+  top: 0;
+  }
+
+.twitter_image_frame > img {
+  display: block;
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  left: 30;
+  width: 100%;
+  margin: auto;
+  }
+
+.twitter_name {
+  padding-left: 55px;
+  line-height: 20px;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  font-size: 16px;
+}
+
+// Body = displays tweets
+.twitter_list {
+  box-sizing: border-box;
+}
+
+.tweet {
+  border-top-style: solid;
+  border-color: lightgrey;
+  padding: 10px 8px;
+}
+
+.tweet_text {
+box-sizing: border-box;
+}
+
+.tweet_text_date {
+  text-align: right;
+  padding-top: 4px;
+  font-size: 12px ;
+}
+
+.twitter_footer {
+  border-top-style: solid;
+  border-color: lightgrey;
+  padding: 10px 8px;
+  font-style: italic;
+  font-size: 12px;
+}