Exact match when deleting stream (#68)

When deleting a logstream from s3 avoid deleting 
other prefixes which starts with same stream_name 
for which delete request was made.

For example, when deleting stream named test, such
streams are also deleted because they share same prefix test
teststream
testlongrun
testapplication

Fix:
Use delimiter at the end of stream name so that only 
those prefix are matched where stream name is exactly 
first component of path on s3. i.e test/ instead of test. 
This will match only logstreams named test.

Author: trueleo

server/src/s3.rs

@@ -175,7 +175,7 @@ impl S3 {
             .client
             .list_objects_v2()
             .bucket(&S3_CONFIG.s3_bucket_name)
-            .prefix(stream_name)
+            .prefix(format!("{}/", stream_name))
             .into_paginator()
             .send();