Support for BigCouch array-format sequence IDs

BigCouch is now using arrays as sequence IDs; TouchDB didn't format these properly.
Fixes #218.

Source/ChangeTracker/TDChangeTracker.m

@@ -78,8 +78,13 @@ - (NSString*) changesFeedPath {
                                               kModeNames[_mode], _heartbeat*1000.0];
     if (_includeConflicts)
         [path appendString: @"&style=all_docs"];
-    if (_lastSequenceID)
-        [path appendFormat: @"&since=%@", TDEscapeURLParam([_lastSequenceID description])];
+    id seq = _lastSequenceID;
+    if (seq) {
+        // BigCouch is now using arrays as sequence IDs. These need to be sent back JSON-encoded.
+        if ([seq isKindOfClass: [NSArray class]] || [seq isKindOfClass: [NSDictionary class]])
+            seq = [TDJSON stringWithJSONObject: seq options: 0 error: nil];
+        [path appendFormat: @"&since=%@", TDEscapeURLParam([seq description])];
+    }
     if (_limit > 0)
         [path appendFormat: @"&limit=%u", _limit];
     if (_filterName) {

Source/TDPuller.h

@@ -33,11 +33,11 @@
 @interface TDPulledRevision : TD_Revision
 {
 @private
-    NSString* _remoteSequenceID;
+    id _remoteSequenceID;
     bool _conflicted;
 }
 
-@property (copy) NSString* remoteSequenceID;
+@property (copy) id remoteSequenceID;
 @property bool conflicted;
 
 @end

Source/TDPuller.m

@@ -171,7 +171,7 @@ - (void) changeTrackerReceivedChanges: (NSArray*)changes {
     for (NSDictionary* change in changes) {
         @autoreleasepool {
             // Process each change from the feed:
-            NSString* remoteSequenceID = [change[@"seq"] description];
+            id remoteSequenceID = change[@"seq"];
             NSString* docID = change[@"id"];
             if (!docID || ![TD_Database isValidDocumentID: docID])
                 continue;
@@ -243,7 +243,7 @@ - (void) changeTrackerStopped:(TDChangeTracker *)tracker {
 - (void) processInbox: (TD_RevisionList*)inbox {
     // Ask the local database which of the revs are not known to it:
     LogTo(SyncVerbose, @"%@: Looking up %@", self, inbox);
-    NSString* lastInboxSequence = [inbox.allRevisions.lastObject remoteSequenceID];
+    id lastInboxSequence = [inbox.allRevisions.lastObject remoteSequenceID];
     NSUInteger total = _changesTotal - inbox.count;
     if (![_db findMissingRevisions: inbox]) {
         Warn(@"%@ failed to look up local revs", self);

Source/TDReplicator_Tests.m

@@ -152,7 +152,7 @@ static void deleteRemoteDB(void) {
     [db open];
 
     id lastSeq = replic8(db, kRemoteDBURLStr, NO, nil);
-    CAssertEqual(lastSeq, @"2");
+    CAssertEqual(lastSeq, @2);
 
     CAssertEq(db.documentCount, 2u);
     CAssertEq(db.lastSequence, 3);