Fixed timeseries uses 2 parallal arrays

* So the only consolation with using arraylist to represent timeseries
  was that the gets would be in constant time since it is a offset based
  seek. When I wrote the implementation for FixedTimeseries, i didn't
  really keep this in mind somehow. So what I did was to store the data
  points within one array and just the starting and ending timestamp. I
  thought that this would save space and went ahead with this.

* Right now when I sit down to write the fetch implementations, I
  realized that this also becomes a O(n) operation since I would have to
  "generate" timestamps for the region requested. I don't have them
  already since they are not stored. Only the starting and ending points
  were stored.

* Got rid of this problem now. I use a 2 parallal array implementation
  so gets would be just a plain select from both the arrays at the same
  offsets.