Api page

Initial version of an API. It adds some basic functions to grab pool information, returning data as JSON encoded data.

Functionality added so far:

| API Action |Arguments | Desctipion |
| ------------- |:-------------:| :-----|
| `getblockcount` | none | Get current block height in blockchain |
| `getblocksfound` | `limit` | Get last `limit` blocks found |
| `getcurrentworkers` | none | Get amount of current active workers |
| `getdifficulty` | none | Get current difficulty in blockchain |
| `getestimatedtime` | none | Get estimated time to next block based on pool hashrate (seconds) |
| `getpoolhashrate` | none | Get current pool hashrate |
| `getpoolsharerate` | none | Get current pool share rate (shares/s) |
| `gettimesincelastblock` | none | Get time since last block found (seconds) |