Add Relative Strength Indicator (RSI) study to QuantFigure.studies

		Parameters:
			periods : int or list(int)
				Number of periods
			rsi_upper : int 
				bounds [0,100]
				Upper (overbought) level
			rsi_lower : int
				bounds [0,100]
				Lower (oversold) level
			showbands : boolean
				If True, then the rsi_upper and
				rsi_lower levels are displayed
			column :string
				Defines the data column name that contains the 
				data over which the study will be applied. 
				Default: 'close'
			name : string
				Name given to the study
			str : string
				Label factory for studies
				The following wildcards can be used:
					{name} : Name of the column
					{study} : Name of the study
					{period} : Period used
				Examples:
					'study: {study} - period: {period}'
		kwargs: 
			legendgroup : bool
				If true, all legend items are grouped into a 
				single one
			All formatting values available on iplot()

def add_rsi(self,periods=20,rsi_upper=70,rsi_lower=30,showbands=True,column=None,
						   name='',str=None,**kwargs):
		"""
		Add Relative Strength Indicator (RSI) study to QuantFigure.studies

		Parameters:
			periods : int or list(int)
				Number of periods
			rsi_upper : int 
				bounds [0,100]
				Upper (overbought) level
			rsi_lower : int
				bounds [0,100]
				Lower (oversold) level
			showbands : boolean
				If True, then the rsi_upper and
				rsi_lower levels are displayed
			column :string
				Defines the data column name that contains the 
				data over which the study will be applied. 
				Default: 'close'
			name : string
				Name given to the study
			str : string
				Label factory for studies
				The following wildcards can be used:
					{name} : Name of the column
					{study} : Name of the study
					{period} : Period used
				Examples:
					'study: {study} - period: {period}'
		kwargs: 
			legendgroup : bool
				If true, all legend items are grouped into a 
				single one
			All formatting values available on iplot()
		"""
		if not column:
			column=self._d['close']
		str=str if str else '{name}({column},{period})'

		study={'kind':'rsi',
			   'name':name,
			   'params':{'periods':periods,'column':column,
						 'str':str},
			  'display':utils.merge_dict({'legendgroup':True,'rsi_upper':rsi_upper,
						 'rsi_lower':rsi_lower,'showbands':showbands},kwargs)}
		self._add_study(study)