Merge branch 'pr_1280' into development-proposed

Conflict: configs/config-picocoin.h was both edited and removed.
Resolution: removed, since this is the whole point of PR #1280 and the
changes in development are no longer relevant.
diff --git a/ChangeLog b/ChangeLog
index 5f49c0b..13fd5d7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -11,6 +11,7 @@
    * Fix tag lengths and value ranges in the documentation of CCM encryption.
      Contributed by Mathieu Briand.
    * Fix typo in a comment ctr_drbg.c. Contributed by Paul Sokolovsky.
+   * Remove support for the library reference configuration for picocoin.
 
 = mbed TLS 2.7.0 branch released 2018-02-03