Fix crypto

A recent change in synapse shown that the various classes handling crypto were broken.
All the crypto code has been refactored in the SDK and the local code has been adapted.

build.gradle

@@ -66,6 +66,7 @@ buildscript {
 
 repositories {
     maven { url "https://kamax.io/maven/releases/" }
+    maven { url "https://kamax.io/maven/snapshots/" }
     mavenCentral()
 }
 
@@ -80,7 +81,7 @@ dependencies {
     compile "org.springframework.boot:spring-boot-starter-thymeleaf:1.5.10.RELEASE"
 
     // Matrix Java SDK
-    compile 'io.kamax:matrix-java-sdk:0.0.8'
+    compile 'io.kamax:matrix-java-sdk:0.0.11'
 
     // ed25519 handling
     compile 'net.i2p.crypto:eddsa:0.1.0'
@@ -94,9 +95,6 @@ dependencies {
     // HTTP connections
     compile 'org.apache.httpcomponents:httpclient:4.5.3'
 
-    // JSON
-    compile 'com.google.code.gson:gson:2.8.1'
-
     // Phone numbers validation
     compile 'com.googlecode.libphonenumber:libphonenumber:8.7.1'