text: Title: possible coding error on bbands.py
  Body: **Which version are you running? The lastest version is on Github. Pip is for major releases.**
  ```python
  import pandas_ta as ta
  print(ta.version)
  ```
  0.3.14b0
  
  **Upgrade.**
  ```sh
  $ pip install -U git+https://github.com/twopirllc/pandas-ta
  ```
  
  **Describe the bug**
  Possible coding error at line 45 at pandas-ta/pandas_ta/volatility/bbands.py
  ```python
          percent = bandwidth.shift(offset)
  ```
  
  
  
  
  **Expected behavior**
  PERCENT = (close - LOWER) / (UPPER - LOWER) with shift(offset)
  ```python
      # Offset
      if offset != 0:
          lower = lower.shift(offset)
          mid = mid.shift(offset)
          upper = upper.shift(offset)
          bandwidth = bandwidth.shift(offset)
          percent = percent.shift(offset)
  ```
  